Information device

ABSTRACT

Problems exist in areas such as image visibility, endurance of the device, precision, miniaturization, and electric power consumption in an information device having a conventional resistive film method or optical method pen input function. Both EL elements and photoelectric conversion elements are arranged in each pixel of a display device in an information device of the present invention having a pen input function. Information input is performed by the input of light to the photoelectric conversion elements in accordance with a pen that reflects light by a pen tip. An information device with a pen input function, capable of displaying a clear image without loss of brightness in the displayed image, having superior endurance, capable of being miniaturized, and having good precision can thus be obtained.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 10/012,370, filed on Dec. 12, 2001 now U.S. Pat. No. 6,747,290,which claims the benefit of a foreign priority application filed inJapan on Dec. 12, 2000 as Serial No. 2000-376760. This applicationclaims priority to each of these prior applications, and the disclosuresof the prior applications are considered part of (and are incorporatedby reference in) the disclosure of this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information device having a functionfor inputting information by using means such as a pen. In particular,the present invention relates to an information device in which peninput operations are performed on a screen of a display device. Thepresent invention relates to an EL display device using EL elements asthe display device, and further, relates to electronic devices, such asportable information devices, having the information device of thepresent invention.

Note that, in this specification, the term EL element denotes an ELelement utilizing both light emission from singlet excitons(fluorescence) and light emission from triplet excitons(phosphorescence).

2. Description of the Related Art

The demand for pen input method portable information devices has risenin terms of miniaturization and operability. The pen input method is amethod for the input of information by using a specialized pen orarbitrary pen, and by either contacting pen tip to a display screen, orbringing the pen tip close to the display screen.

Namely, input of information corresponding to positions indicated by thepen tip on the display screen is performed. The display screen alsofunctions as a pen input screen. It is necessary to specify thepositions indicated by the pen on the pen input screen with this peninput method, and methods such as a resistive film method and an opticalmethod exist as means for the pen input.

The resistive film method is explained first.

FIG. 7 is a cross sectional diagram showing the structure of a resistivefilm pen input device. Note that a pen input device 7711 is formedoverlapping with and on the upper portion of a display device 7708. Thedisplay device 7708 has a display portion 7709 and a peripheral circuit7710.

A movable electrode 7701 and a fixed electrode 7702 sandwich dot spacers7704 in the pen input device 7711, and both are connected in parallelwith a gap of approximately 100 to 300 μm by a lamination material 7703.The movable electrode 7701 and the fixed electrode 7702 are formed byconductive materials having transparency so that images projected on thedisplay portion 7709 of the display device 7708 can be seen through thepen input device 7711. In general, an indium tin oxide (ITO) film isused as the conductive material having transparent properties.

The movable electrode 7701 touches the fixed electrode 7702 in aposition indicated by the input pen 7704 on the pen input device 7711with the resistive film method (input point A in FIG. 7). At this time,in the method, the position of the input point A is read out as theratio of resistances R1 and R2 from two position detection electrodes7706 and 7707.

Specifically, an example of performing position read out is shown inFIG. 8. A pressure is applied by an input pen 807 from a movableelectrode 801 side and there is contact between the movable electrode801 and a fixed electrode 802 at the input point A. A voltage is appliedbetween two electrodes 803 and 804 of the movable electrode 801 here,and an electric potential gradient is generated within the movableelectrode 801. By measuring the electric potential V_(A) of the inputpoint A at this point, resistance values R_(x1) and R_(x2) from theelectrode 803 and the electrode 804 to the input point A can be found.If the film quality of the movable electrode 801 is assumed to beuniform, then the resistance values R_(x1) and R_(x2) are proportionalto the distances from the electrodes 803 and 804 to the input point A,respectively.

Similarly, a voltage is applied between two electrodes 805 and 806 ofthe fixed electrode 802, and an electric potential gradient within thefixed electrode 802 is generated. By knowing the electric potentialV_(A) of the input point A at this point, resistance values R_(y1) andR_(y2) from the electrode 805 and the electrode 806 to the input point Acan be found. If the film quality of the fixed electrode 802 is assumedto be uniform here, then the resistance values R_(y1) and R_(y2) areproportional to the distances from the electrodes 805 and 806 to thepoint A, respectively. The position of the input point A can thus bedetermined.

Note that the method of measuring the electric potential of the inputpoint A for measuring the position of the input point A is not limitedto the above structure, and various other methods can also be used.

An optical method pen input device is explained next. A schematicdiagram of an upper surface of the optical method pen input device isshown in FIG. 9A.

If a pen tip of an input pen 901 makes contact to an input portion 902,the contact position is detected. The position detection operation isexplained.

X-1 light emitting diodes (hereafter referred to as LEDs) 2 ₁ to 2 _(x)are arranged in a right edge portion in the periphery of the inputportion 902, and x-1 phototransistors (hereafter referred to as PTs) 3 ₁to 3 _(x) are arranged in a left edge portion of the input portion 902,opposite the LEDs 2 ₁ to 2 _(x). The light emitting diodes and thephototransistors are embedded in a frame 4.

Y-1 LEDs 5 ₁ to 5 _(y) are arranged in a lower edge portion, and y-1 PTs6 ₁ to 6 _(y) are arranged in an upper edge portion, opposite the LEDs 5₁ to 5 _(y). The LEDs and the PTs are embedded in the frame 4.

The LEDs 2 ₁ to 2 _(x) and the PTs 3 ₁ to 3 _(x) form x-1 horizontaldirection touch input lines, and the LEDs 5 ₁ to 5 _(y) and the PTs 6 ₁to 6 _(y) form y-1 vertical direction touch input lines.

The term touch input lines refer to paths along which light emitted fromthe LEDs travels when input to the PTs between pairs of opposing LEDsand PTs.

Note that although PTs are used as the components having referencenumerals 3 ₁ to 3 _(x) and 6 ₁ to 6 _(y), there is no limitationassociated with PTs, and other components can be freely used providedthat they are photoelectric conversion elements that convert light intoan electric signal.

In order to increase the directionality of light emitted from the LEDs 2₁ to 2 _(x) and 5 ₁ to 5 _(x), and made incident on the PTs 3 ₁ to 3_(x) and 6 ₁ to 6 _(y), hole shaped slits 7 are formed in front of theframe 4 in which each of the elements is embedded.

FIG. 9B is a cross sectional diagram along a line segment a-a′ of FIG.9A. A display device 910 is formed in a portion below the pen inputdevice. The display device 910 is structured by a display portion 911and a peripheral circuit 912. Differing from the resistive film method,it is possible to directly see images displayed in the display portion911.

FIG. 9A is again referenced.

The emission of light and the receiving of light are performed one pairat a time from the edge for the pairs of opposing LEDs and PTs. Thisoperation (hereafter referred to as scanning) is performed at the sametime for the horizontal direction touch input lines and the verticaldirection touch input lines in the pen input device having the abovestructure.

One point within the input portion 902 is indicated by the input pen901. The input point A within FIG. 9A is indicated. Light is cutoffbetween two touch lines 2 _(n) to 3 _(n) and 5 _(m) to 6 _(m) at thispoint, and the position A at which the input pen 901 contacts isrecognized.

It is necessary to mechanically change the shape of the movableelectrode as information is input with the resistive film method. Themovable electrode thus fatigues with repeated shape change, and there isthe possibility of it being broken. This becomes an endurance problem.

Further, even if damage does not reach actual breakage, the ITO filmconductivity becomes non-uniform due to repeated deformation and in thecase where minute cracks on the order of micrometers in size are formedduring manufacturing process. Therefore, problems in the precision ofinput pen location detection develop.

In addition, the display device image is read out through the twoelectrodes, the movable electrode and the fixed electrode. Thetransmittivity of the transparent electrodes is not 100% at this time,and therefore light from the display device is attenuated and brightnessof the image falls, generating visibility problems with the screen. Theintensity of light emitted form the display device consequently must bemade stronger so as to increase the brightness of the image, and thereis a problem with increased power consumption of the device.

Further, when stress opposing substrate is applied from the outside ofthe device, and the distance between the two electrodes, the movableelectrode and the fixed electrode, becomes equal to or less than 40 μm,then a problem exists in which Newton rings appear due to aninterference effect of light reflected between the two electrodes.

In addition, this is a capacitor structure in which the two electrodesare arranged in parallel, and therefore consumption is large when abattery electric power source is used. This is a large problem forportable information devices in which low power consumption is desired.

On the other hand, there are no mechanical endurance problems with theoptical method pen input device because it is not necessary for the thinfilms to repeatedly be deformed as with the resistive film method.Further, the display device is not seen through transparent electrodes,and therefore problems with screen visibility are also few.

However, for cases where light emitted from the light emitting elementsis not received in a straight line by the paired light receivingelements, there is a possibility that recognition will not be made evenif the input pen or the like indicates the position.

Furthermore, it is necessary to form columns of light emitting elementsand light receiving elements, slits and the like on the display device,and therefore there is a problem in that it is difficult to make thedevice smaller.

SUMMARY OF THE INVENTION

With an information device having a pen input function according to thepresent invention, both EL (electroluminescence) elements andphotoelectric conversion elements are arranged in pixels of a displaydevice, and input of information is performed by a pen reflecting lightin a tip of the pen.

EL elements are self light emitting elements, and are mainly used in ELdisplay devices. EL display devices are also referred to as organic ELdisplay devices (organic EL displays, OELDs) and organic light emittingdiodes (OLEDs).

The EL element is structured by sandwiching an EL layer between a pairof electrodes (an anode and a cathode). The EL layer normally has alamination structure. A lamination structure proposed by Tang, et al. ofEastman Kodak Corp. having a hole transporting layer, a light emittinglayer, and an electron transporting layer can be typically given. Thisstructure is known to emit light with extremely high efficiency.

Further, other lamination structures may also be formed on theelectrode, such as a lamination of a hole injecting layer, a holetransporting layer, a light emitting layer, and an electron transportinglayer, and a lamination structure of a hole injecting layer, a holetransporting layer, a light emitting layer, an electron transportinglayer, and an electron injecting layer. A material such as a fluorescentpigment may also be doped into the light emitting layer.

The term EL layer indicates all of the layers formed between a pair ofelectrodes in this specification. The layers such as the hole injectinglayer, the hole transporting layer, the light emitting layer, theelectron transporting layer, and the electron injecting layer statedabove are therefore all contained within the category of EL layers. Apredetermined voltage is applied to the above structured EL layers fromthe pair of electrodes. Recombination of the carrier thus occurs in thelight emitting layer, and light is emitted.

Note that the EL layer is not limited to one having a laminationstructure in which the layers are clearly separated, such as the holeinjecting layer, the hole transporting layer, the light emitting layer,the electron transporting layer, and the electron injecting layer.Namely, the EL layer may also take a structure having, a layer in whichmaterials structuring the layers such as the hole injecting layer, thehole transporting layer, the light emitting layer, the electrontransporting layer, and the electron injecting layer are mixed.

For example, an EL layer with a structure having a mixed layer betweenan electron transporting layer and a light emitting layer, the mixedlayer structured by a material structuring an electron transportinglayer (hereafter referred to as an electron transporting material) and amaterial structuring a light emitting layer (hereafter referred to as alight emitting material), may also be used.

Note that low molecular weight materials, high molecular weightmaterials, and intermediate molecular weight materials may all be usedfor the EL layer.

Note also that, within this specification, the term intermediatemolecular weight material indicates a material which does not havesublimation properties and in which the length of molecules linkedtogether is 10 μm or less.

Photodiodes and the like can be used as the photoelectric conversionelements. The term photodiode denotes an element having an anodeelectrode, a cathode electrode, and a photoelectric conversion layerbetween the anode electrode and the cathode electrode in thisspecification.

Note that photodiodes are not limited to this structure, and PINstructure photodiodes having a photoelectric conversion layerconstituted of a p-type semiconductor layer, an n-type semiconductorlayer and an i-type (intrinsic) semiconductor layer between the p-typesemiconductor layer and the n-type semiconductor layer may also be used.Further, a PN type photodiode constituted of a p-type semiconductorlayer and an n-type semiconductor layer may also be used.

Furthermore, an element having a photoelectric conversion layer madefrom an organic compound or the like may also be used as thephotoelectric conversion element.

If light is irradiated after applying an inverse bias voltage betweenthe cathode electrode and the anode electrode of a photodiode (hereafterreferred to as between the photodiode electrodes), then the voltagebetween the electrodes is lowered by a carrier developing due to thelight. The amount that the voltage drops becomes larger as the intensityof the irradiated light becomes stronger. Light is thus detected as anelectric signal by the ratio of the voltage in the case where light isirradiated to the photodiode and the voltage in the case where there isno irradiation of light.

EL elements and photodiodes are formed in a matrix shape on the samesubstrate, and the operation of each of the EL elements and thephotodiodes is controlled by using thin film transistors (TFTs)similarly formed in a matrix shape.

An information device that displays a clear image without losing imagebrightness and that is excellent in durability, enablingminiaturization, having good precision, and having a low electric powerconsumption pen input function can thus be obtained.

Structures of the information device of the present invention are statedbelow.

In accordance with the present invention, there is provided aninformation device having:

a plurality of pixels; an input pen: and an EL element and aphotoelectric conversion element in each of the plurality of pixels;

characterized in that:

-   -   light emitted from the EL elements is reflected by the input        pen; and the light reflected by the input pen performs        information input by being input to the photoelectric conversion        elements.

The information device may also be characterized in that the EL elementsand the photoelectric conversion elements are formed on the samesubstrate.

The information device may also be characterized in that thephotoelectric conversion elements are photodiodes.

In accordance with the present invention, there is provided aninformation device having:

a plurality of pixels;

an EL display source signal line driver circuit;

an EL display gate signal line driver circuit;

a plurality of EL display source signal lines;

a plurality of EL display gate signal lines;

a plurality of electric power source supply lines; and

an input pen;

characterized in that:

-   -   the EL display source signal line driver circuit inputs signals        to the plurality of EL display source signal lines;    -   the EL display gate signal line driver circuit inputs signals to        the plurality of EL display gate signal lines;    -   the plurality of pixels each have an EL display portion and a        sensor portion;    -   the EL display portion and the sensor portion are formed on the        same substrate;    -   the EL display portion has a switching TFT, an EL driver TFT,        and an EL element;    -   a gate electrode of the switching TFT is connected to one of the        plurality of EL display gate signal lines;    -   one of a source region and a drain region of the switching TFT        is connected to one of the plurality of EL display source signal        lines, and the other of the source region and the drain region        of the switching TFT is connected to a gate electrode of the EL        driver TFT;    -   one of a source region and a drain region of the EL driver TFT        is connected to one of the plurality of electric power source        supply lines, and the other of the source region and the drain        region of the EL driver TFT is connected to the EL element;    -   the sensor portion has a photodiode;    -   light emitted by the EL element is reflected by the input pen;        and    -   input of information is performed in accordance with the light        reflected by the input pen being input to the photodiode.

In accordance with the present invention, there is provided aninformation device having:

a plurality of pixels;

a sensor source signal line driver circuit;

a sensor gate signal line driver circuit;

a plurality of sensor output wirings;

a plurality of sensor gate signal lines;

a plurality of reset gate signal lines;

a plurality of sensor electric power source lines; and

-   -   an input pen;

characterized in that:

-   -   the sensor source signal line driver circuit reads in signals        from the plurality of sensor output wirings;    -   the sensor gate signal line driver circuit outputs signals to        the plurality of sensor gate signal lines and to the plurality        of reset gate signal lines;    -   the plurality of pixels each have an EL display portion and a        sensor portion;    -   the EL display portion and the sensor portion are formed on the        same substrate;    -   the sensor portion has a selection TFT, a buffer TFT, a reset        TFT, and a photodiode;    -   a gate electrode of the selection TFT is connected to one of the        plurality of sensor gate signal lines;    -   one of a source region and a drain region of the selection TFT        is connected to one of the plurality of sensor output wirings,        and the other of the source region and the drain region of the        selection TFT is connected to one of a source region and a drain        region of the buffer TFT;    -   one of the source region and the drain region of the buffer TFT,        which is not connected to the selection TFT, is connected to one        of the plurality of sensor electric power source lines;    -   a gate electrode of the buffer TFT is connected to the        photodiode and to a source region or a drain region of the reset        TFT;    -   one of the source region and the drain region of the reset TFT        which is not connected to the buffer TFT, is connected to one of        the plurality of sensor electric power source lines;    -   a gate electrode of the reset TFT is connected to one of the        plurality of the reset gate signal lines;    -   the EL display portion has an EL element;    -   light emitted by the EL element is reflected by the input pen;        and    -   input of information is performed in accordance with the light        reflected by the input pen being input to the photodiode.

In accordance with the present invention, there is provided aninformation device having:

a plurality of pixels;

an EL display source signal line driver circuit;

an EL display gate signal line driver circuit;

a sensor source signal line driver circuit;

a sensor gate signal line driver circuit;

a plurality of EL display source signal lines;

a plurality of EL display gate signal lines;

a plurality of electric power source supply lines;

a plurality of sensor output wirings;

a plurality of sensor gate signal lines;

a plurality of reset gate signal lines,

a plurality of sensor electric power source lines; and

an input pen;

characterized in that:

-   -   the EL display source signal line driver circuit outputs signals        to the plurality of EL display source signal lines;    -   the EL display gate signal line driver circuit outputs signals        to the plurality of EL display gate signal lines;    -   the sensor source signal line driver circuit reads in signals        from the plurality of sensor output wirings;    -   the sensor gate signal line driver circuit outputs signals to        the plurality of sensor gate signal lines and to the plurality        of reset gate signal lines;    -   the plurality of pixels each have an EL display portion and a        sensor portion;    -   the EL display portion and the sensor portion are formed on the        same substrate;    -   the EL display portion has a switching TFT, an EL driver TFT,        and an EL element;    -   a gate electrode of the switching TFT is connected to one of the        plurality of EL display gate signal lines;    -   one of a source region and a drain region of the switching TFT        is connected to one of the plurality of EL display source signal        lines, and the other of the source region and the drain region        of the switching TFT is connected to a gate electrode of the EL        driver TFT;    -   one of a source region and a drain region of the EL driver TFT        is connected to one of the plurality of electric power source        supply lines, and the other of the source region and the drain        region of the EL driver TFT is connected to the EL element;    -   the sensor portion has a selection TFT, a buffer TFT, a reset        TFT, and a photodiode;    -   a gate electrode of the selection TFT is connected to one of the        plurality of sensor gate signal lines;    -   one of a source region and a drain region of the selection TFT        is connected to one of the plurality of sensor output wirings,        and the other of the source region and the drain region of the        selection TFT is connected to one of a source region and a drain        region of the buffer TFT;    -   one of the source region and the drain region of the buffer TFT,        which is not connected to the selection TFT, is connected to one        of the plurality of sensor electric-power source lines;    -   a gate electrode of the buffer TFT is connected to the        photodiode and to a source region or a drain region of the reset        TFT;    -   one of the source region and the drain region of the reset TFT,        which is not connected to the buffer TFT, is connected to one of        the plurality of sensor electric power source lines;    -   a gate electrode of the reset TFT is connected to one of the        plurality of the reset gate signal lines;    -   light emitted by the EL element is reflected by the input pen;        and    -   input of information is performed in accordance with the light        reflected by the input pen being input to the photodiode.

The information device may also be one in which the EL display sourcesignal line driver circuit and the EL display gate signal line drivercircuit are formed on the same substrate as the EL display portion andthe sensor portion.

The information device may also be one in which the sensor source signalline driver circuit and the sensor gate signal line driver circuit areformed on the same substrate as the EL display portion and the sensorportion.

The information device may also be characterized in that the EL displaysource signal line driver circuit, the EL display gate signal linedriver circuit, the sensor source signal line driver circuit and thesensor gate signal line driver circuit are formed on the same substrateas the EL display portion and the sensor portion.

The information device may also be characterized in that the photodiodehas an anode electrode, a cathode electrode, and a photoelectricconversion layer sandwiched between the anode electrode and the cathodeelectrode.

The information device may also be characterized in that thephotoelectric conversion layer is structured by an organic material.

The information device may also be characterized in that the photodiodehas a p-type semiconductor layer, an n-type semiconductor layer, and aphotoelectric conversion layer sandwiched between the p-typesemiconductor layer and the n-type semiconductor layer.

The information device may also be characterized in that thephotoelectric conversion layer is structured by an amorphoussemiconductor.

The information device may also be characterized in that:

light emitted from the EL elements is irradiated to a surface of anobject;

the light irradiated to the surface of the object is reflected by thesurface of the object; and

information regarding the surface of the object is input as an image inaccordance with the light reflected by the surface of the object beinginput to the photoelectric conversion elements.

The information device may also be characterized in that informationregarding the surface of the object is biological information.

The information device may also be characterized in that the biologicalinformation is a palm print.

The information device may also be characterized in that the biologicalinformation is a finger print.

The information device may also be a portable information terminal or aPDA.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic diagram of an information device of the presentinvention;

FIG. 2 is a schematic diagram of an upper surface and a cross section ofa optical sensor of the present invention;

FIG. 3 is a circuit diagram of a pixel portion of a display panel of aninformation device of the present invention having an attached imagesensor:

FIG. 4 is a cross sectional diagram of an information device of thepresent invention;

FIG. 5 is a cross sectional diagram of an information device of thepresent invention;

FIGS. 6A to 6C are upper surface diagrams and cross sectional diagramsof an information device of the present invention;

FIG. 7 is a diagram showing the structure of a conventional resistivefilm pen input device;

FIG. 8 is a diagram showing the structure of a conventional resistivefilm pen input device;

FIGS. 9A and 9B are diagrams showing structures of a conventionaloptical pen input device;

FIGS. 10A to 10C are diagrams showing a method of manufacturing aninformation device of the present invention;

FIGS. 11A to 11C are diagrams showing the method of manufacturing allinformation device of the present invention;

FIGS. 12A to 12C are diagrams showing the method of manufacturing aninformation device of the present invention;

FIGS. 13A to 13B are diagrams showing the method of manufacturing aninformation device of the present invention;

FIGS. 14A to 14B are diagrams showing the method of manufacturing aninformation device of the present invention;

FIGS. 15A to 15B are diagrams of electronic devices applying aninformation device of the present invention;

FIG. 16 is a diagram showing a timing chart for driving an informationdevice of the present invention;

FIG. 17 is a diagram showing a timing chart for driving an informationdevice of the present invention;

FIG. 18 is a diagram showing a timing chart for driving an informationdevice of the present invention;

FIG. 19 is a diagram showing the structure of a photoelectric conversionelement of an information device of the present invention;

FIG. 20 is a cross sectional diagram of an information device of thepresent invention; and

FIGS. 21A and 21B are diagrams of electronic equipment applying allinformation device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment mode of the present invention is explained.

FIG. 1 shows a schematic diagram of an information device having a peninput function of the present invention.

A method in which information is input by indicating an inside portionof a combination display portion and input portion in accordance with aninput pen which reflects light in a pen tip is explained in theembodiment mode. Each pixel in the combination display portion and inputportion is structured by an EL display portion having an EL element, anda sensor portion having a photoelectric conversion element. The ELdisplay portion and the sensor portion are driven by signals from an ELdisplay source signal line driver circuit, an EL display gate signalline driver circuit, a sensor source signal line driver circuit, and asensor gate signal line driver circuit arranged in the peripheral of thecombination display portion and input portion.

The driver circuits (the EL display source signal line driver circuit,the EL display gate signal line driver circuit, the sensor source signalline driver circuit, and the sensor gate signal line driver circuit) areformed on the same substrate as the combination display portion andinput portion here.

Signals from the EL display source signal line driver circuit aretransmitted to the EL display portion of each pixel by EL display sourcesignal lines S, and signals from the EL display gate signal line drivercircuit are transmitted to the EL display portion of each pixel by ELdisplay gate signal lines G.

The sensor source signal line driver circuit reads in signals from thesensor portion of each pixel by sensor output wirings SS, and the sensorgate signal line driver circuit transmits signals to the sensor portionof each pixel by sensor gate signal lines SG.

Note that EL element electric power source lines (electric power sourcesupply lines) arranged in each pixel, sensor electric power sourcelines, and reset signal lines (reset gate signal lines), and the likeare not shown in FIG. 1.

Each pixel of the combination display portion and input portion performsdisplay in its EL display portion. At the same time, light irradiatedfrom the EL display portion is reflected at the pen tip of the inputpen, and the light is input to the sensor portion (light input region)in the vicinity of the position indicated by the pen tip. The positionindicated by the input pen is thus recognized.

A specific circuit structure of the combination display portion andinput portion is explained next.

FIG. 2 is a diagram showing an example of a circuit structure of thecombination display portion and input portion.

A combination display portion and input portion 2201 has EL displaysource signal lines S1 to Sx, EL display gate signal lines G1 to Gy,electric power source supply lines V1 to Vx, sensor output wirings SS1to SSx, sensor gate signal lines SG1 to SGy, reset gate signal lines RG1to RGy, and a sensor electric power source line VB.

The combination display portion and input portion 2201 has a pluralityof pixels 2202. Each of the plurality of pixels 2202 has one of the ELdisplay source signal lines S1 to Sx, one of the EL display gate signallines G1 to Gy, one of the electric power source supply lines V1 to Vx,one of the sensor output wirings SS1 to SSx, one of the sensor gatesignal lines SG1 to SGy, one of the reset gate signal lines RG1 to RGy,and the sensor electric power source line VB.

The sensor output wirings SS1 to SSx are connected to constant electriccurrent sources 2203-1 to 2203-x, respectively.

A detailed structure of the pixels 2202 of FIG. 2 is shown in FIG. 3.Note that the EL display source signal line S shows one of the ELdisplay source signal lines S1 to Sx, and that the EL display gatesignal line G shows one of the EL driver gate signal lines G1 to Gy. Inaddition, an electric power source supply line V shows one of theelectric power source supply lines V1 to Vx. The sensor output wiring SSshows one of the sensor output wirings SS1 to SSx, and the sensor gatesignal line SG shows one of the sensor gate signal lines SG1 to SGy.

The pixel has an EL display portion 3311 and a sensor portion 3312.

The EL display portion 3311 is structured by an EL element 3301, aswitching TFT 3302, an EL driver TFT 3303, and a capacitor 3304. Notethat it is not always necessary to form the capacitor 3304 provided thata parasitic capacitance of a gate electrode of the EL driver TFT 3303 isactively utilized.

A gate electrode of the switching TFT 3302 is connected to the ELdisplay gate signal line G, one of a source region and a drain region ofthe switching TFT 3302 is connected to the EL display source signal lineS, and the other is connected one electrode of the capacitor 3304 and tothe gate electrode of the EL driver TFT 3303. The other electrode of thecapacitor 3304 is connected to the electric power source supply line V.One of a source region and a drain region of the EL driver TFT 3303 isconnected to the electric power source supply line V, and the other isconnected to the EL element 3301.

Among an anode and a cathode of the EL element 3301, the one connectedto the source region or the drain region of the EL driver TFT 3303becomes a pixel electrode, and the one not connected to the sourceregion or the drain region of the EL driver TFT 3303 becomes an opposingelectrode.

The sensor portion 3312 is structured by a photodiode 3305, a selectionTFT 3306, a buffer TFT 3307, and a reset TFT 3308.

A Schottky structure photodiode in which a photoelectric conversionlayer is sandwiched between an anode electrode and a cathode electrodeis used as the structure of the photodiode 3305 in the embodiment mode.

Light made incident to the photodiode is absorbed by the photoelectricconversion layer and forms a carrier. The amount of the carrier formedby this light depends upon the amount of light absorbed by thephotoelectric conversion layer.

Although a photodiode having the above stated structure is used as thephotoelectric conversion element for converting light to an electricsignal here, there are no limitations imposed upon this structure, andPIN photodiodes, PN photodiodes, avalanche diodes, and the like can alsobe used.

Note that PIN photodiodes are structured by a p-type semiconductorlayer, an n-type semiconductor layer, and an i-type (intrinsic)semiconductor layer sandwiched between the p-type semiconductor layerand the n-type semiconductor layer. The i-type semiconductor layer isalso referred to as a photoelectric conversion layer here.

Further, the light absorptivity of the photoelectric conversion layercan be increased by using an amorphous semiconductor such as anamorphous silicon film as the photoelectric conversion layer of thesephotodiodes.

In addition, a photoelectric conversion element having a photoelectricconversion layer structured from an organic material, or the like mayalso be used as the photoelectric conversion element.

A gate electrode of the selection TFT 3306 is connected to the sensorgate signal line SG, one of a source region and a drain region of theselection TFT 3306 is connected to the sensor output wiring SS, and theother is connected to a source region or a drain region of the bufferTFT 3307. Among the source region and the drain region of the buffer TFT3307, the one not connected to the selection TFT 3306 is connected tothe sensor electric power source line VB. A gate electrode of the resetTFT 3308 is connected to the reset gate signal line RG, one of a sourceregion and a drain region of the reset TFT 3308 is connected to thereset electric power source line VB, and the other is connected to agate electrode of the buffer TFT 3307 and to the photodiode 3305.

The sensor electric power source line VB is maintained at a fixedelectric potential (standard electric potential). The sensor outputwiring SS is connected to a constant electric current source.

Note that circuits having known structures may be used as the EL displaysource signal line driver circuit, the sensor source signal line drivercircuit, the EL display gate signal line driver circuit, and the sensorgate signal line driver circuit.

A method of operation of the combination display portion and pixelportion having the above structure is explained using the circuitdiagrams of FIG. 2 and FIG. 3, and the timing charts of FIG. 17 and FIG.18.

First, a method of operating the EL display portion is explained usingFIG. 2, FIG. 3, and FIG. 17.

Note that a method of performing display in which an analog signal isinput to the source signal lines S1 to Sx (hereafter referred to as ananalog method) is explained here.

The switching TFT 3302 and the EL driver TFT 3303 are n-channel TFTshere, but the switching TFT 3302 and the EL driver TFT 3303 may each beeither an n-channel TFT or a p-channel TFT. However, in order to have afixed source electric potential and the desired operation when the ELelement 3301 anode is the pixel electrode, it is preferable that the ELdriver TFT 3303 be a p-channel TFT. Conversely, it is preferable thatthe EL driver TFT 3303 be an n-channel TFT for cases in which thecathode of the EL element 3301 is the pixel electrode.

All of the switching TFTs 3302 connected to the EL display gate signalline G1 are placed in a conductive state by a signal input to the ELdisplay gate signal line G1.

A period during which a certain one of the EL display gate signal linesis selected is referred to as one line period. In particular, a periodduring which the EL display gate signal line G1 is selected is referredto as a first line period L1. Analog signals are input to the EL displaysource signal lines S1 to Sx in order during the line period L1. Thevoltage of the analog signals input to the EL display source signallines is applied to the capacitor 3304 and to the gate electrode of theEL driver TFT 3303. The EL driver TFT 3303 causes an electric currentbetween the source and the drain and corresponding to the voltage of theanalog signal applied to the gate electrode to flow in the EL element3301 from the electric power source supply line V. The EL element 3301emits light having a brightness corresponding to the electric current.

Next, the EL display gate signal line G2 is selected, and all of theswitching TFTs 3302 connected to the EL display gate signal line G2 areplaced in a conductive state. A second line period L2 thus begins.Signal voltages are then input in order to the EL display source signallines S1 to Sx. The signal voltage is applied to the gate electrode ofthe EL driver TFTs 3303, and an electric current between the source andthe drain corresponding to the voltage of the analog signal applied tothe gate electrode flows in the EL element 3301 from the electric powersource supply line V. The EL element 3301 emits light at a brightnesscorresponding the electric current.

One frame period F1 is completed by repeating the above operations forall of the EL display gate signal lines G1 to Gy. A second frame periodF2 begins next, and one image is displayed by repeating theseoperations.

A method of operating the sensor portion is explained next using FIG. 2,FIG. 3, and FIG. 18.

The reset TFT 3308 is an n-channel TFT, the buffer TFT 3307 is ap-channel TFT, and the selection TFT 3306 is an n-channel TFT here, butthe reset TFT 3308, the buffer TFT 3307, and the selection TFT 3306 mayeach be n-channel TFTs or p-channel TFTs. Note that it is preferablethat the polarities of the reset TFT 3308 and the buffer TFT 3307 beopposites.

First, all of the reset TFTs 3308 connected to the reset gate signalline RG1 are placed in a conductive state by a reset gate signal lineRG1 signal. The reset gate signal line RG1 is assumed to be selected atthis time. Note that all of the reset TFTs 3308 connected to the otherreset gate signal lines RG2 to RGy are in non-conductive states. Theelectric potential of the sensor electric power source line VB in afirst pixel line is applied to the gate electrode of the buffer TFT 3307through the reset TFT 3308. A reverse bias voltage is thus appliedbetween the electrodes of the photodiode 3305. At this point, the sourceregion of the buffer TFT 3307 is maintained at an electric potential inwhich the electric potential difference between the source region andthe gate region of the buffer TFT 3307 is subtracted from the electricpotential of the sensor electric power source line VB (standard electricpotential).

All of the selection TFTs 3306 connected to the sensor gate signal lineSG1 are in non-conductive states at this time in accordance with thesensor gate signal line SG1 signal.

A period during which the reset gate signal lines are selected isreferred to as a reset period RS in this specification.

Next, the reset gate signal line RG1 signal changes, and all of thereset TFTs 3308 connected to the reset gate signal line RG1 are placedin a non-conductive state. The reset gate signal line is assumed to beunselected at this time. If light is irradiated to the photodiode 3305,then an electric current flows between the electrodes of the photodiode3305, and the reverse bias voltage between the electrodes of thephotodiode 3305 applied during the reset period becomes lower. All ofthe selection TFTs 3306 connected to the sensor gate signal line SG1 arethen placed in a conductive state in accordance with the signal input tothe sensor gate signal line SG1.

A period from when the reset gate signal line is placed in an unselectedstate until the selection TFT corresponding to the pixels of the sameline is selected is referred to as a sampling period ST. In particular,a period from when the reset gate signal line RG1 is placed in anunselected state until the selection gate signal line SG1 is selected isreferred to as a first sampling period ST1.

The reverse bias voltage between the electrodes of the photodiode 3305becomes smaller as time passed during the sampling period ST1. Thedegree at which the reverse bias voltage is reduced depends upon theintensity of light irradiated to the photoelectric conversion layer ofthe photodiode 3305. The electrode of the photodiode 3305 not connectedto the gate electrode of the buffer TFT 3307 is maintained at a fixedelectric potential here. The electric potential of the electrode of thephotodiode 3305 connected to the gate electrode of the buffer TFT 3307therefore drops.

The electric potential drop causes the electric potential of the gateelectrode of the buffer TFT 3307 to fall.

The source regions of the buffer TFTs 3307 of each pixel are connectedto the constant electric current sources 2203-1 to 2203-x, respectively,through the drain and source of the selection TFTs 3306 here, andtherefore the buffer TFTs 3307 work as source followers. Consequently,the voltage between the gate and the source of the buffer TFTs 3307 arealways maintained equal. If the electric potential of the gate electrodeof the buffer TFT 3307 changes due to changes in the electric potentialbetween the electrodes of the photodiode 3305, then the electricpotential of the source region of the buffer TFT 3307 also changes bythe same amount. The sensor gate signal line SG1 is selected after thesampling period ST1, and changes in the electric potential of the sourceregion of the buffer TFTs 3307 are output to the sensor output signalwirings SS1 to SSx.

The sensor gate signal line SG1 is then placed in an unselected state.

On the other hand, the reset gate signal line RG2 is selected when thereset gate signal line RG1 is placed in an unselected state. All of thereset TFTs 3308 connected to the reset gate signal line RG2 becomeconductive, and a second line reset period RS begins. The reset gatesignal line RG2 then is placed in an unselected state and a second linesampling period ST2 begins. Note that although the first sampling periodST1 and the second sampling period ST2 have different starting times,they have the same length.

The reverse bias voltage between the electrodes of the photodiodes alsosimilarly drops during the second sampling period ST2 in correspondencewith the intensity of light input to the sensor portions of each pixel.All of the selection TFTs 3306 connected to the sensor gate signal lineSG2 become conductive in accordance with the sensor gate signal line SG2signal after the second sampling period ST2. Then, changes in theelectric potential between the electrodes of the photodiodes 3305 inputto the gate electrodes of the buffer TFTs 3307 are output to the sensoroutput wirings SS1 to SSx as changes in the electric potential of thesource regions of the buffer TFTs 3307.

The sensor gate signal line SG2 is then placed in an unselected state.

By repeating the above operations for all of the sensor gate signallines SG1 to SGy, the intensity of light input to all of the sensorportions 3312 of the pixels of the combination display portion and inputportion 2201 is read in as corresponding voltage signals.

The EL display portion thus performs image display and at the same timethe light reflected in the pen tip of the input pen is detected in thesensor portion. The coordinates of the pixels into which light reflectedfrom the pen tip of the input pen is input can thus be specified. Theposition indicated by the input pen can therefore be specified.

EMBODIMENTS

Embodiments of the present invention are discussed below.

Embodiment 1

An example of manufacturing an information device of the presentinvention discussed in the embodiment mode is explained in Embodiment 1using the cross sectional diagram of FIG. 4. Note that the pixelstructure is similar to that shown in FIG. 3 in the embodiment mode.

Reference numeral 401 denotes a switching TFT, reference numeral 402denotes an EL driver TFT, reference numeral 403 denotes a reset TFT,reference numeral 404 denotes a buffer TFT, and reference numeral 405denotes a selection TFT.

Further, reference numeral 406 denotes an anode electrode, 407 denotes aphotoelectric conversion layer, and reference numeral 408 denotes acathode electrode. A photodiode 421 is formed by the anode electrode406, the photoelectric conversion layer 407, and the cathode electrode408. Reference numeral 414 denotes a sensor wiring, and the sensorwiring is electrically connected to the cathode 408 and to an externalelectric power source. Furthermore, the anode electrode 406 of thephotodiode 421 and a drain region of the reset TFT 403 are electricallyconnected.

The anode electrode 406 of the photodiode 421 is formed by a materialhaving transparent properties here.

Reference numeral 409 denotes a pixel electrode (anode), referencenumeral 410 denotes an EL layer, and reference numeral 411 denotes anopposing electrode (cathode). An EL element 422 is formed by the pixelelectrode (anode) 409, the EL layer 410, and the opposing electrode(cathode) 411. Note that reference numeral 412 denotes a bank, and thatthe bank separates the EL layers 410 of mutually adjacent pixels.

The pixel electrode 409 of the EL element 422 is formed by a materialhaving transparent properties here.

The EL element 422 irradiates light to a substrate 430 side in FIG. 4. Areflection plate 423 of a pen tip of an input pen 424 approaches fromthe side of the substrate 430 on which components such as TFTs are notformed. A portion of the light irradiated from the EL elements 422 ofthe pixels is thus reflected by the reflection plate 423 of the pen tipof the input pen 424, and is input to the photoelectric conversionlayers 407 of the photodiodes 421 of the sensor portions of the pixelsin the vicinity of the position which the input pen 424 contacts. Theposition indicated by the pen tip of the input pen 424 can therefore bespecified.

The switching TFT 401, the reset TFT 403, and the selection TFT 405 areall n-channel TFTs in Embodiment 1. Further, the EL driver TFT 402 andthe buffer TFT 404 are p-channel TFTs. Note that the present inventionis not limited by this structure. The switching TFT 401, the EL driverTFT 402, the buffer TFT 404, the selection TFT 405, and the reset TFT403 can therefore be n-channel TFTs or p-channel TFTs.

However, for cases in which the source region or the drain region of theEL driver TFT 402 is electrically connected to the anode 409 of the ELelement 422, as in Embodiment 1, it is preferable that the EL driver TFT402 be a p-channel TFT. Conversely, it is preferable that the EL driverTFT 402 be an n-channel TFT when the source region or the drain re ionof the EL driver TFT 402 is electrically connected to the cathode of theEL element 422.

Further, for cases in which the anode electrode 406 of the photodiode421 is electrically connected to the reset TFT 403, it is preferablethat the reset TFT 403 be an n-channel TFT and that the buffer TFT 404be a p-channel TFT. Conversely, it is preferable that the reset TFT 403be a p-channel TFT and that the buffer TFT 404 be an n-channel TFT ifthe cathode electrode of the photodiode 421 is connected to the resetTFT 403 and the sensor wiring 414 is connected to the anode electrode.

Embodiment 2

An example in which the direction of light emitted by an EL elementdiffers in an information device having the structure discussed inEmbodiment 1 is explained in Embodiment 2 using FIG. 5. Note that thepixel structure is similar to that shown by FIG. 3 in the embodimentmode.

Reference numeral 501 denotes a switching TFT, reference numeral 502denotes an EL driver TFT, reference numeral 503 denotes a reset TFT,reference numeral 504 denotes a buffer TFT, and reference numeral 505denotes a selection TFT.

Further, reference numeral 506 denotes a cathode electrode, referencenumeral 507 denotes a photoelectric conversion layer, and referencenumeral 508 denotes an anode electrode. A photodiode 521 is formed bythe cathode electrode 506, the photoelectric conversion layer 507, andthe anode electrode 508. Reference numeral 514 denotes a sensor wiring,and the sensor wiring is electrically connected to the anode 508 and toan external electric power source. Furthermore, the cathode electrode506 of the photodiode 521 and a drain region of the reset TFT 503 areelectrically connected.

The anode electrode 508 of the photodiode 521 is formed by a materialhaving transparent properties here.

Reference numeral 509 denotes a pixel electrode (cathode), referencenumeral 510 denotes an EL layer, and reference numeral 512 denotes anopposing electrode (anode). An EL element 522 is formed by the pixelelectrode (cathode) 509, the EL layer 510, and the opposing electrode(anode) 512. Note that reference numeral 512 denotes a bank, and thatthe bank separates the EL layers 510 of mutually adjacent pixels.

The opposing electrode 512 of the EL element 522 is formed by a materialhaving transparent properties here.

The EL element 522 irradiates light in a direction opposite a substrate530 in the information device having the structure shown in FIG. 5.

A reflection plate 523 is attached to a pen tip of an input pen 524 inorder to reflect light.

The EL element 522 irradiates light in a direction opposite thesubstrate 530 in FIG. 5. The reflection plate 523 of the pen tip of theinput pen 524 approaches from the side of the substrate 530 on whichcomponents such as TFTs are formed. A portion of the light irradiatedfrom the EL elements 522 of the pixels is thus reflected by thereflection plate 523 of the pen tip of the input pen 524, and is inputto the photoelectric conversion layers 507 of the photodiodes 521 of thesensor portions of the pixels in the vicinity of the position indicatedby the input pen 524 makes contact. The position indicated by the pentip of the input pen 524 can therefore be specified.

The switching TFT 501, the EL driver TFT 502, the buffer TFT 504, andthe selection TFT 505 are all n-channel TFTs in Embodiment 2. Further,the reset TFT 503 is a p-channel TFT. Note that the present invention isnot limited by this structure. The switching TFT 501, the EL driver TFT502, the buffer TFT 504, the selection TFT 505, and the reset TFT 503can therefore be n-channel TFTs or p-channel TFTs.

However, for cases in which the source region or the drain region of theEL driver TFT 502 is electrically connected to the cathode 509 of the ELelement 522, as in Embodiment 2, it is preferable that the EL driver TFT502 be an n-channel TFT. Conversely, it is preferable that the EL driverTFT 502 be a p-channel TFT when the source region or the drain region ofthe EL driver TFT 502 is electrically connected to the anode of the ELelement 522.

Further, for cases in which the cathode electrode 506 of the photodiode521 is electric-ally connected to the reset TFT 503, it is preferablethat the reset TFT 503 be a p-channel TFT and that the buffer TFT 504 bea n-channel TFT. Conversely, it is preferable that the reset TFT 503 bean n-channel TFT and that the buffer TFT 504 be a p-channel TFT if theanode electrode of the photodiode 521 is connected to the reset TFT 503and the sensor wiring 514 is connected to the cathode electrode.

Embodiment 3

The operation method of a combination of display portion and inputportion, which is different from that shown in the embodiment mode, isdescribed in this embodiment. The structure of the combination ofdisplay portion and input portion is the same as the structure shown inthe embodiment mode, and therefore the explanation is omitted and FIGS.2 and 3 may be referenced. Note that the operation method of the sensoris the same as that shown by the embodiment mode, and FIG. 18 may bereferenced.

The operation method of the EL display portion is different in thisembodiment. A timing chart showing operation method of the EL displayportion of this embodiment is shown in FIG. 16.

First, one frame period F is divided into N subframe periods SF1 to SFN.The number of subframe periods in one frame period also increases as thenumber of gray scales increases. Note that, when the combination ofdisplay portion and input portion displays an image, one frame period Fdenotes a period during which the EL display portion of all pixels ofthe combination of display portion and input portion display one image.

It is preferable that 60 or more frame periods be provided each secondfor the case of this embodiment. By setting the number of imagesdisplayed each second to 60 or greater, it becomes possible to visuallysuppress image flicker.

The subframe period is divided into an address period Ta and a sustainperiod Ts. The address period is a period within one subframe periodduring which a digital video signal is inputted to all pixels. Note thatthe digital video signal is a digital signal having image information.The sustain period (also referred to as a turn-on period) denotes aperiod during which EL elements are placed in a state of emitting lightor not emitting light in accordance with the digital video signalinputted to the pixels in the address period and display is performed.Note that the digital video signal denotes the digital signal havingimage information.

The address periods (Ta) of SF1 to SFN are taken as address periods Ta1to TaN, and the sustain periods (Ts) of SF1 to SFN are taken as sustainperiods Ts1 to TsN.

The electric potential of the electric power source supply lines V1 toVx is maintained at a predetermined electric potential (electric powersource potential).

First, the electric potential of the opposing electrode of the ELelements 3301 is maintained at the same height as the electric powersource potential in the address period Ta.

Next, all of the switching TFTs 3302 connected to the EL display gatesignal line G1 are placed in a conductive state in accordance with asignal inputted to an EL display gate signal G1. The digital videosignal is then inputted to the EL display source signal lines S1 to Sx.The digital video signal has “0” or “1” information, and one of the “0”and “1” digital video signals is a signal having a “Hi” voltage, whilethe other is a signal having a “Lo” voltage.

The digital video signal inputted to the source signal lines S1 to Sx isthen inputted to the gate electrodes of the EL driver TFTs 3303 throughthe switching TFTs 3302 in a conductive state.

All of the switching TFTs 3302 connected to the EL display gate signalline G1 are then placed in a non-conductive state, and all of theswitching TFTs 3302 connected to the EL display gate signal line G2 areplaced in a conductive state in accordance with a gate signal inputtedto the EL display gate signal line G2. The digital video signal is theninputted to the source signal lines S1 to Sx. The digital video signalinputted to EL display the source signal lines S1 to Sx is inputted tothe gate electrodes of the EL driver TFTs 3303 through the switchingTFTs 3302 in a conductive state.

The above operations are repeated through the EL display gate signalline Gy, and the digital video signal is inputted to the gate electrodesof the EL driver TFTs 3303 of all the pixels, and the address period iscompleted.

The sustain period Ts begins simultaneously with the completion of theaddress period Ta. All of the switching TFTs 3302 are in anon-conductive state in the sustain period Ts. The electric potential ofthe opposing electrodes of all the EL elements 3301 has a height of theelectric potential difference between the electric power sourcepotential to the level at which the EL elements 3301 will emit lightwhen the electric potential of the electric power source is applied tothe pixel electrodes.

When the digital video signal has “0” information, the EL driver TFT3303 is placed in a non-conductive state in this embodiment. The voltageat the degree of luminescence of the EL element 3301 does not impressedbetween the pixel electrode of the EL element 3301 and the opposingelectrode. As a result, the EL element 3301 does not emit light when thedigital video signal having “0” information is inputted to the pixel.

On the other hand, when the digital video signal has “1” information,the EL driver TFTs 3303 are placed in a conductive state. The electricpower source potential is therefore applied to the pixel electrode ofthe EL element 3301. As a result, the EL element 3301 of the pixel intowhich the digital video signal having “1” information is inputted emitslight.

The EL elements are thus placed in a state in which they emit light ordo not emit light in accordance with the information of the digitalvideo signal input to the pixels, and the pixels perform display.

One subframe period is completed at the same time as the sustain periodTs is complete. The next subframe period then appears, and once againthe address period Ta begins. The sustain period Ts again beings afterthe digital video signal is input to all of the pixels. Note that theorder of appearance of the subframe periods SF1 to SFN is arbitrary.

Similar operations are then repeated in the remaining subframe periods,and display is performed. After completing all of the N subframeperiods, one image is displayed, and one frame period is completed. Whenone frame period is complete, the subframe period of the next frameperiod appears, and the above stated operations are repeated.

The lengths of the address periods Ta1 to TaN of the respective nsubframe periods are each the same in the present invention. Further,the ratio of lengths of the N sustain periods Ts1,. . . , Tsn isexpressed as Ts1:Ts2:Ts3: . . . :Ts(N−1):Tsn=2⁰:2⁻¹:2⁻²: . . .:2^(−(N−2)):2^(−(N−1)).

The gray-scale of each pixel is determined in accordance with duringwhich subframe periods in one frame period the pixel is made to emitlight. For example, in the case that Ts1:Ts2:Ts3: . . . :Ts(N−1):TsN=2⁰:2⁻¹:2⁻²: . . . :2^(−(N−2)):2^(−(N−1)), when N=8, and takingthe brightness of pixels which emit light in all of the sustain periodsTs1 to Ts8 as having a value of 100%. pixels which emit light in Ts1 andTs2 can express a brightness of 75%, and for a case of selecting Ts3.Ts5, and Ts8, a brightness of 16% can be expressed.

As mentioned above, the technique of displaying image, in which thedigital signal is inputted to the source signal lines S1 to Sx and theEL element of the pixel is emitted light, is referred to digital method.

A method of operating the sensor portion is explained next using FIG. 2,FIG. 3, and FIG. 18.

The reset TFT 3308 is an n-channel TFT, the buffer TFT 3307 is ap-channel TFT, and the selection TFT 3306 is an n-channel TFT here, butthe reset TFT 3308, the buffer TFT 3307, and the selection TFT 3306 mayeach be n-channel TFTs or p-channel TFTs. Note that it is preferablethat the polarities of the reset TFT 3308 and the buffer TFT 3307 beopposites.

First, all of the reset TFTs 3308 connected to the reset gate signalline RG1 are placed in a conductive state by the reset gate signal lineRG1 signal. The reset gate signal line RG1 is assumed to be selected atthis time. Note that all of the reset TFTs 3308 connected to the otherreset gate signal lines RG2 to RGy are in non-conductive states. Theelectric potential of the sensor electric power source line VB in afirst pixel line is applied to the gate electrode of the buffer TFT 3307through the reset TFT 3308. A reverse bias voltage is thus appliedbetween the electrodes of the photodiode 3305. At this point, the sourceregion of the buffer TFT 3307 is maintained at an electric potential inwhich the electric potential difference between the source region andthe gate region of the buffer TFT 3307 is subtracted from the electricpotential of the sensor electric power source line VB (standard electricpotential).

All of the selection TFTs 3306 connected to the sensor gate signal lineSG1 are in non-conductive states at this time in accordance with thesensor gate signal line SG1 signal.

The period during which the reset gate signal lines are selected isreferred to as the reset period RS in this specification.

Next, the reset gate signal line RG1 signal changes, and all of thereset TFTs 3308 connected to the reset gate signal line RG1 are placedin a non-conductive state. The reset gate signal line is assumed to beunselected at this time. If light is irradiated to the photodiode 3305,then an electric current flows between the electrodes of the photodiode3305, and the reverse bias voltage between the electrodes of thephotodiode 3305 applied during the reset period becomes lower. All ofthe selection TFTs 3306 connected to the sensor gate signal line SG1 arethen placed in a conductive state in accordance with the signal input tothe sensor gate signal line SG1.

The period from when the reset gate signal line is placed in anunselected state until the selection TFT corresponding to the pixels ofthe same line is selected is referred to as the sampling period ST. Inparticular, the period from when the reset gate signal line RG1 isplaced in an unselected state until the selection gate signal line SG1is selected is referred to as the first sampling period ST1.

The reverse bias voltage between the electrodes of the photodiode 3305becomes smaller as time passed during the sampling period ST1. Thedegree at which the reverse bias voltage is reduced depends upon theintensity of light irradiated to the photoelectric conversion layer ofthe photodiode 3305. The electrode of the photodiode 3305 not connectedto the gate electrode of the buffer TFT 3307 is maintained at a fixedelectric potential here. The electric potential of the electrode of thephotodiode 3305 connected to the gate electrode of the buffer TFT 3307therefore drops.

The electric potential drop causes the electric potential of the gateelectrode of the buffer TFT 3307 to fall.

The source regions of the buffer TFTs 3307 of each pixel are connectedto the constant electric current sources 2203-1 to 2203-x, respectively,through the drain and source of the selection TFTs 3306 here, andtherefore the buffer TFTs 3307 work as source followers. Consequently,the voltage between the gate and the source of the buffer TFTs 3307 arealways maintained equal. If the electric potential of the gate electrodeof the buffer TFT 3307 changes due to changes in the electric potentialbetween the electrodes of the photodiode, then the electric potential ofthe source region of the buffer TFT 3307 also changes by the sameamount. The sensor gate signal line SG1 is selected after the samplingperiod ST1, and changes in the electric potential of the source regionof the buffer TFTs 3307 are output to the sensor output wirings SS1 toSSx.

The sensor gate signal line SG1 is then placed in all unselected state.

On the other hand, the reset gate signal line RG2 is selected when thereset gate signal line RG1 is placed in an unselected state. All of thereset TFTs 3308 connected to the reset gate signal line RG2 becomeconductive, and the second line reset period RS begins. The reset gatesignal line RG2 then is placed in an unselected state and the secondline sampling period ST2 begins. Note that although the first samplingperiod ST1 and the second sampling period ST2 have different startingtimes, they have the same length.

The reverse bias voltage between the electrodes of the photodiodes alsosimilarly drops during the second sampling period ST2 in correspondencewith the intensity of light input to the sensor portions of each pixel.All of the selection TFTs 3306 connected to the sensor gate signal lineSG2 become conductive in accordance with the sensor gate signal line SG2signal after the second sampling period ST2. Then, changes in theelectric potential between the electrodes of the photodiodes 3305 inputto the gate electrodes of the buffer TFTs 3307 are output to the sensoroutput wirings SS1 to SSx as changes in the electric potential of thesource regions of the buffer TFTs 3307.

The sensor gate signal line SG2 is then placed in an unselected state.

By repeating the above operations for all of the sensor gate signallines SG1 to SGy, the intensity of light input to all of the sensorportions 3312 of the pixels of the combination display portion and inputportion 2201 is read in as corresponding voltage signals.

The EL display portions of the pixels do not emit light in addressperiods Ta1 to TaN for cases in which the combination pixel portion andinput portion of the information device of the present invention isoperating with the above method of operation. Originally, therefore, iflight from the EL elements is reflected by the pen tip of the input penand input to the photodiodes as shown in Embodiment 1 and in Embodiment2, the light is not input to the photodiodes of the pixels to which thesignal must be input, and the reverse bias voltage between theelectrodes of the photodiodes does not drop. In other words, informationfor specifying the position of the pen tip of the input pen is not inputin the address periods Ta1 to TaN.

Further, subframe periods during which the pixels do not emit lightexist in the pixels indicated by the pen tip of the input pen inaccordance with the gray scale displayed. In other words, originallylight is not input to the photodiodes of pixels to which signals shouldbe input during the subframe periods in which the pixels do not emitlight, and information for specifying the position of the pen tip of theinput pen is not input.

However, the length of a period for reading in one screen of the sensorportion is normally set to be sufficiently longer than the addressperiods Ta1 to TaN of the EL display portion.

Namely, the lengths of the sampling periods ST1 to STy of the sensorportion of each pixel are set to be sufficiently longer than the lengthsof the address periods Ta1 to TaN.

The period during which the EL elements emit light can therefore besufficiently maintained during the period in which one screen of thesensor portion is read in.

Further, the period for reading in one screen of the sensor portion isgenerally equal to or longer than one frame period of the EL displayportion. Light is therefore irradiated intermittently to the pen tip ofthe input pen from pixels in the vicinity of the location indicated bythe pen tip of the input pen during a period of time whose lengthcorresponds to the sum of the subframe periods during which the ELelements emit light within the period for reading in one screen of thesensor portion. Light can therefore be input to the photodiodes of thepixels in the vicinity of the location indicated by the pen tip of theinput pen by using this irradiated light.

The position of the pen tip of the input pen can thus be specified.

Note that it is possible to freely combine the present embodiment withEmbodiment 1 and Embodiment 2.

Embodiment 4

An input pen can be used not only to perform information input, but callalso be used as an image sensor in an information device of the presentinvention.

FIG. 20 is a schematic diagram of a case in which an information deviceof the present invention is used as an image sensor and reads ininformation from a surface of an object.

A circuit structure of a combination display portion and input portionof the image device is similar to that of the embodiment mode, andtherefore its explanation is omitted here. Further, portions in theschematic diagram of FIG. 20 that are similar to portions in FIG. 4 areshown using the same reference symbols, and their explanation is alsoomitted here.

A method of driving the combination display portion and input portioncan use a technique similar to the technique shown in the embodimentmode and in Embodiment 3, and therefore such explanation is omittedhere.

An object to be read (a target object 425) approaches the side, wherepen input is performed, of the combination display portion and inputportion of the information device of the present invention. The ELelements 422 of each pixel are made to emit light by a technique similarto that shown in the embodiment mode and in Embodiment 3. Light isirradiated to the target object 425 using the light emitted from the ELelements 422. In other words, the EL elements 422 of each pixel are usedas illumination devices for reading in information of the target object425.

It is therefore preferable that the brightness of the light emitted bythe EL elements of each pixel all be set to the same level when usingthe image device of the present invention as an image sensor.

Namely, analog signals input from EL source signal lines in each of thepixels are set to be equal when driving the EL elements of each pixel inaccordance with an analog method like that shown in the embodiment mode.

On the other hand, all of the pixels are made to emit light for periodsof time having the same length within one frame period for cases ofdriving the EL elements of each pixel by a digital method such as thatshown in Embodiment 3. Note that in order to irradiate light ascontinuously as possible, it is preferable that the EL elements of eachof the pixels be set so as to emit light during all sustain periodswithin-one frame period.

The light irradiated to the target object 425 is thus reflected by thesurface of the target object 425 to be read, and is input to thephotodiodes 421 of the sensor portion of each pixel. The input light isconverted into electric signals, is read out by sensor driver circuits(a sensor source signal line driver circuit and a sensor gate signalline driver circuit), and information regarding the surface of thetarget object 425 can be obtained as an image.

Although the explanation is performed here using an information devicehaving the structure shown in Embodiment 1, the target object can alsoapproach from the side of the combination display portion and pixelportion substrate on which TFTs are formed using an information devicehaving the structure shown in FIG. 5 in Embodiment 2. Informationregarding the surface of the target object can also be read in.

Note that it is possible to implement the present embodiment by freelycombining it with any of Embodiments 1 to 3.

Embodiment 5

The manufacturing method of the combination of display portion and inputportion of the information device of the present invention is describedwith references FIGS. 10A to 14B.

Referring to FIG. 10A, a substrate 200 is prepared first. The substrate200 in this embodiment is made of glass such as barium borosilicateglass represented by the Corning # 7059 glass or the Corning # 1737glass that are products of Corning Incorporated, or alumino borosilicateglass. The material of the substrate 200 is not limited as long as it isa light transmissive substrate, and a quartz substrate may be used.Alternatively, a plastic substrate may be used if it has a heatresistance that can endure the treatment temperature in this embodiment.

In addition, a stainless substrate may be used as a substrate 200.However, the stainless substrate is effective only when the lightemitting from the EL element is radiating to opposite direction againstthe substrate 200, because the stainless substrate is not transparent.

Next, an insulating film is formed from silicon oxide on the substrate200 so as to cover the substrate 200. The insulating film may be asilicon oxide film, a silicon nitride film or a silicon oxynitride film.For example, it may be a laminate of a silicon oxynitride film formed byplasma CVD from SiH₄, NH₃ and N₂O to a thickness of 250 to 800 nm(preferably 300 to 500 nm) and a hydrogenated silicon oxynitride filmsimilarly formed from SiH₄ and N₂O to a thickness of 250 to 800 nm(preferably 300 to 500 nm). The insulating film here uses silicon oxideand is formed into a single layer having a thickness of 0.5 to 1.5 μm.The material of the insulating film is not limited to silicon oxide.

The insulating film is then polished by CMP to form a planarizationinsulating film 201. A known CMP technique can be used here. Slurrygenerally used in polishing an oxide film is a solid-liquid dispersionsystem slurry obtained by dispersing a 100 to 1000 nmφ abrasive in asolution containing a reagent such as a PH adjuster. This embodimentuses a silica slurry (PH=10 to 11) in which 20 wt % of fumed silicaparticles obtained by pyrolizing silicon chloride gas are dispersed in asolution added with potassium hydroxide.

After forming the planarization insulating film 201, semiconductorlayers 202 to 206 are formed on the planarization insulating film 201.The semiconductor layers 202 to 206 are obtained by forming asemiconductor film having an amorphous structure through a known method(sputtering LPCVD or plasma CVD), crystallizing the amorphoussemiconductor film through a known crystallization processing (lasercrystallization, thermal crystallization, or thermal crystallizationthat uses a catalyst such as nickel), and patterning the obtainedcrystalline semiconductor film into a desired shape. The semiconductorlayers 202 to 206 each has a thickness of 25 to 80 nm (preferably 30 to60 nm). No limitation is put on the material of the crystallinesemiconductor film but silicon, a silicon germanium alloy(Si_(X)Ge_(1−X)(X=0.0001 to 0.02)), or the like is preferable. In thisembodiment, an amorphous silicon film is formed by plasma CVD to athickness of 55 nm and a solution containing nickel is then retained onthe amorphous silicon film. Dehydrogenation (at 500° C. for an hour) isperformed on the amorphous silicon film before thermal crystallization(at 550° C. for four hours) is conducted. Then the film is subjected tolaser annealing for improving the crystallinity to obtain thecrystalline silicon film. The crystalline silicon film is patterned byusing photolithography to form the semiconductor layers 202 to 206.

The semiconductor layers 202 to 206 then may be doped with a minuteamount of impurity element (boron or phosphorus) for controlling thethreshold of the TFTs.

When laser crystallization is chosen to form the crystallinesemiconductor film, a pulse oscillation or continuous wave excimerlaser, YAG laser or YVO₄ laser can be used. In using such laser, laserlight emitted from a laser oscillator is preferably collected by anoptical system into a linear beam before irradiating the semiconductorfilm. Conditions for the crystallization may suitably be chosen by anoperator. However, appropriate conditions in the case of using anexcimer laser include setting the pulse oscillation frequency to 300 Hzand setting the laser energy density to 100 to 400 mJ/cm² (typically 200to 300 mJ/cm²). If the laser is an YAG laser, its second harmonic isused to set the pulse oscillation frequency to 30 to 300 kHz and thelaser energy density is appropriately set to 300 to 600 mJ/cm²(typically 350 to 500 mJ/cm²). The laser light is then collected into alinear beam with a width of 100 to 1000 μm, for example, 400 μm, and thesubstrate is irradiated with the linear beam until the laser scanningcovers the entire surface of the substrate. The overlap ratio of thelinear laser light beams in this case is 50 to 98%.

A gate insulating film 209 is formed next to cover the semiconductorlayers 202 to 206. The gate insulating film 209 is formed by plasma CVDor sputtering from an insulating film containing silicon to a thicknessof 40 to 150 nm. In this embodiment, silicon oxynitride film(composition ratio: Si=32%. O=59%, N=7%, H=2%) with a thickness of 110nm is formed bad plasma CVD. The gate insulating film is not limited toa silicon oxynitride film, of course, but a single layer or a laminatelayer of other silicon-containing films can be used as the gateinsulating film.

When a silicon oxide film is used, the film is formed by plasma CVDwhile mixing TEOS (tetraethyl orthosilicate) with O₂, and discharging ata reaction pressure of 40 Pa, a substrate temperature of 300 to 400° C.,and a high frequency (13.56 MHz) power density of 0.5 to 0.8 W/cm². Thesilicon oxide film thus formed displays excellent characteristics as thegate insulating film through a subsequent thermal annealing at 400 to500° C.

Next, as shown in FIG. 10A, a first conductive film 210 a with athickness of 20 to 100 nm and a second conductive film 210 b with athickness of 100 to 400 nm are layered on the gate insulating film 209.In this embodiment, the first conductive film 210 a is a 30 nm thick TaNfilm, on which a W film having a thickness of 370 nm and serving as thesecond conductive film 210 b is placed to form a laminate. The TaN filmis formed by sputtering with Ta as the target in atmosphere containingnitrogen. The W film is formed by sputtering with W as the target.Alternatively, the W film may be formed by thermal CVD using tungstenhexafluoride (WF₆). In either case, the film has to be lowered inresistivity in order to use it as the gate electrode, and theresistivity of the W film is desirably 20 μΩcm or lower. The resistivityof the W film can be lowered when the grain size in the film isincreased. However, if there are many impurity elements such as oxygenin the W film, crystallization is hindered and the resistivity isincreased. For that reason, the W film in this embodiment is formed bysputtering while using a high purity W target (purity: 99.9999%) andtaking a great care to avoid mixing-in of impurities from the air duringthe film formation. As a result, the W film can have a reducedresistivity of 9 to 20 μΩcm.

The first conductive film 210 a and the second conductive film 210 b inthis embodiment are formed from TaN and W, respectively, but thematerials thereof are not particularly limited. Each of them call beformed of all element selected from the group consisting of Ta, W, Ti,Mo, Al, Cu, Cr and Nd, or of an alloy material or compound materialmainly containing one or more of the elements above. A semiconductorfilm, typically a polycrystalline silicon film, doped with an impurityelement such as phosphorus may also be used. An AgPdCu alloy is alsoincluded in the usable materials. The following combinations of thefirst conductive film and the second conductive film are also suitable;a tantalum (Ta) film for the first conductive film and a W film for thesecond conductive film, a titanium nitride (TiN) film for the firstconductive film and a W film for the second conductive film, a tantalumnitride (TaN) film for the first conductive film and an Al film for thesecond conductive film, and a tantalum nitride (TaN) film for the firstconductive film and a Cu film for the second conductive film.

A resist mask 211 is next formed by photolithography to carry out afirst etching treatment for forming electrodes and wirings (FIG. 10B).The first etching treatment employs first etching conditions and secondetching conditions. In this embodiment, the first etching conditionsinclude: using ICP (Inductively Coupled Plasma) etching; using as anetching gas CF₄, Cl₂ and O₂ and setting the ratio of their respectiveflow rates to 25/25/10 (sccm); and giving an RF (13.56 MHz) power of 500W to a coil-formed electrode at a pressure of 1 Pa to generate plasma.Used here is a dry etching apparatus adopting ICP (model: E645-ICP), aproduct of Matsushita Electric Industrial Co., Ltd. The substrate side(sample stage) also receives an RF (13.56 MHz) power of 150 W so that asubstantially negative self-bias voltage is applied. The W film isetched under the first etching conditions, so that the first conductivelayer is tapered around the edge. The etching rate for etching the Wfilm under the first etching conditions is 200.39 nm/min., whereas theetching rate for etching the TaN film under the first etching conditionsis 80.32 nm/min. Accordingly the selective ratio of W to TaN is about2.5. The taper angle of the W film is about 26° under the first etchingconditions.

In the first etching treatment above, the first conductive layer and thesecond conductive layer are tapered around their edges owing to a propershape of the resist mask 211 and the effect of the bias voltage appliedto the substrate side. The angle of the tapered portions isappropriately 15 to 45°. Thus formed through the first etching treatmentare conductive layers 212 to 216 having a first shape (first conductivelayers 212 a to 216 a and second conductive layers 212 b to 216 b) whichare formed from the first conductive layer and the second conductivelayer. Reference symbol 217 denotes a gate insulating film, and regionsof the gate insulating film which are not covered with the conductivelayers 212 to 216 having the first shape are etched by about 20 to 50nm, thereby forming thinned regions.

Without removing the resist mask, a second etching treatment isconducted next (FIG. 10C). In the etching here, an etching gas obtainedby mixing CF₄, Cl₂ and O₂ is used, ratio of their respective flow ratesis set to 25/25/10 (sccm), and an RF (13.56 MHz) power of 500 W is givento a coil-formed electrode at a pressure of 1 Pa to generate plasma. Thesubstrate side (sample stage) also receives an RF (13.56 MHz) power of20 W so that a substantially negative self-bias voltage is applied. Theetching rate for etching the W film in the second etching treatment is124.62 nm/min., whereas the etching rate for etching the TaN film in thesecond etching treatment is 20.67 nm/min., and the selective ratio of Wto TaN is 6.05. Accordingly, the W film is selectively etched. The taperangle of the W film is 70° after receiving the second etching treatment.Through the second etching treatment, second conductive layers 218 b to222 b are formed. On the other hand, the first conductive layers 218 ato 222 a are barely etched. Denoted by 223 is a gate insulating film,and regions of the (sate insulating film which are not covered with theconductive layers 218 to 222 having the first shape are etched by about20 to 50 nm, thereby forming thinned regions.

The first conductive layer 218 a and the second conductive layer 218 btogether form an electrode, which serves as a buffer TFT of an n-channelTFT to be formed in a later step. The first conductive layer 219 a andthe second conductive layer 219 b together form an electrode, whichserves as a selective TFT of an n-channel TFT to be formed in a laterstep. Similarly, the first conductive layer 220 a and the secondconductive layer 220 b together form Ian electrode, which serves as areset TFT of a p-channel TFT to be formed in a later step. The firstconductive layer 221 a and the second conductive layer 221 b togetherform an electrode, which serves as a switching TFT of an n-channel TFTto be formed in a later step. The first conductive layer 222 a and thesecond conductive layer 222 b together form an electrode, which servesas an EL driver TFT of a p-channel TFT to be formed in a later step.

A first doping treatment is performed next to obtain the state of FIG.11A. In the doping, the second conductive layers 218 b to 222 b are usedas masks against an impurity element and semiconductor layers below thetapered portions of the first conductive layers 218 a to 222 a are dopedwith the impurity element. This embodiment uses plasma doping whilechoosing phosphorus (P) for the impurity element, setting the dose to3.5×10¹², and setting the acceleration voltage to 90 keV. Thus formed ina self-aligning manner are low concentration impurity regions 224 a to228 a, which do not overlap the first conductive layers, and lowconcentration impurity regions 224 b to 228 b, which overlap the firstconductive layers. The concentration of phosphorus (P) in the lowconcentration impurity regions 224 b to 228 b is 1×10¹⁷ to 1×10¹⁸atoms/cm³, and the concentration shows gentle gradient in accordancewith the graduated thickness of the tapered portions of the firstconductive layers 218 a to 222 a. In the semiconductor layers thatoverlap the tapered portions of the first conductive layers 218 a to 222a, the concentration of the impurity element is slightly decreasedtoward the centers from the edges of the tapered portions of the firstconductive layers 218 a to 222 a. However, overall, the concentration isalmost uniform.

Then a resist mask 231 is formed to conduct a second doping treatmentfor doping the semiconductor layers with an impurity element impartingthe n-type conductivity (FIG. 11B). In this doping treatment, ion dopingor ion implanting is employed. Conditions for ion doping include settingthe dose to 1×10¹³ to 5×10¹⁵ atoms/cm² and setting the accelerationvoltage to 60 to 100 keV. In this embodiment, the dose is set to1.5×10¹⁵ atoms/cm² and the acceleration voltage is set to 80 keV. Theimpurity element imparting n-type conductivity is an element belongingto Group 15 in the periodic table, typically, phosphorus (P) or arsenic(As). Phosphorus (P) is used here. In this case, the conductive layers218 to 222 serve as masks against the impurity element imparting then-type conductivity as high concentration impurity regions 232 a to 236a, low concentration impurity regions 232 b to 236 b, which do notoverlap the first conductive layers, and low concentration impurityregions 232 c to 236 c, which overlap the first conductive layers, areformed in a self-aligning manner. The high concentration impurityregions 232 a to 236 a are doped with the impurity element imparting then-type conductivity in a concentration of 1×10²⁰ to 1×10²¹ atoms/cm³.

The semiconductor films for forming the p-channel TFT do not need to bedoped with the impurity element imparting the n-type conductivitythrough the second doping treatment shown in FIG. 11B. Therefore themask 231 is formed so as to cover the semiconductor layers 204 and 206completely, thereby preventing the layers from being doped with then-type impurity element. The mask 231 may not be provided on thesemiconductor layers 204 and 206. In this case, the polarity of thesesemiconductor layers is changed to p-type in a third doping treatment.

After removing the resist mask 231, a resist mask 239 is newly formedfor the third doping treatment. Formed through the third dopingtreatment in the semiconductor layer that is to serve as an active layerof the p-channel TFT are impurity regions 240 a to 240 c and 241 a to241 c doped with an impurity element imparting the conductivity type(p-type) opposite to the conductivity type (n-type) in the second dopingtreatment (FIG. 11C). The first conductive layers 220 b and 222 b areused as masks against the impurity element, and doping of the impurityelement imparting the p-type conductivity is carried out to form theimpurity regions in a self-aligning manner. In this embodiment, theimpurity regions 240 a to 240 c and 241 a to 241 c are formed by iondoping using diborane (B₂H₆). The semiconductor layers for forming then-channel TFTs are covered with the resist mask 239 during the thirddoping treatment. The impurity regions 240 a to 240 c have been dopedwith phosphorus in different concentrations through the first dopingtreatment and the second doping treatment. However, in the third dopingtreatment, the impurity regions 240 a to 240 c are both doped with theimpurity element for imparting the p-type conductivity in aconcentration of 2×10²⁰ to 2×10²¹ atoms/cm³. Therefore the impurityregions 240 a to 240 c have no problem in functioning as a source regionor a drain region of the p-channel TFT.

The next step is to activate the impurity elements used to dope therespective semiconductor layers. This activation step employs thermalannealing using an annealing furnace. The thermal annealing is conductedin nitrogen atmosphere with the oxygen concentration being 1 ppm orless, preferably 0.1 ppm or less, at a temperature of 400 to 700° C.,typically, 500 to 550° C. In this embodiment, the activation is made byheat treatment at 550° C. for four hours. Other usable methods thanthermal annealing include laser annealing and rapid thermal annealing(RTA).

The activation may be carried out before the first interlayer insulatingfilm is formed. However, if the material used for the wiring is weakagainst heat, it is preferred to conduct activation after the interlayerinsulating film (an insulating film containing silicon as mainingredient, e.g., a silicon nitride film) as in this embodiment in orderto protect the wiring and others as well.

Another heat treatment is conducted in atmosphere containing 3 to 100%hydrogen at 300 to 550° C. for one to twelve hours to hydrogenate thesemiconductor layers. In this embodiment, heat treatment is carried outin nitrogen atmosphere containing about 3% of hydrogen at 410° C. for anhour. This step is to terminate dangling bonds in the semiconductorlayers by hydrogen contained in the interlayer insulating film. Otherhydrogenation measures include plasma hydrogenation (that utilizeshydrogen excited by plasma).

Further, the hydrogenation process may also be performed after forming apassivation film.

Impurity regions are formed in the respective semiconductor layers bythe above steps.

Next, the mask 239 made from resist is removed, and a third etchingprocess is performed. The conductive layers 218 to 222 are used as masksin Embodiment 5, and the gate insulating film is etched.

Gate insulating films 243 c to 247 c are formed below the secondconductive layers 243 b to 247 b by the third etching process (See FIG.12A). First conductive layers 243 a to 247 a and the second conductivelayers 243 b to 247 b constitute gate electrodes 243 to 247.

A passivation film 291 is formed next so as to cover the substrate 200.(See FIG. 12B.) A silicon oxide film, a silicon nitride film, or asilicon oxynitride film can be used as the passivation film 291. Forexample, a silicon oxynitride film formed from SiH₄, NH₃, and N₂O with athickness of 250 to 800 nm (preferably 300 to 500 nm) by plasma CVD, anda hydrogenated silicon oxynitride film formed similarly from SiH₄ andN₂O with a thickness of 250 to 800 nm (preferably 300 to 500 nm) may beformed in a lamination layer. The passivation film 291 is formed from asingle layer structure of nitric oxide with a thickness of 0.5 to 1.5 μmin Embodiment 5.

A first interlayer insulating film 249 is formed next. An insulatingfilm containing silicon is formed having a thickness of 100 to 200 nm byplasma CVD or sputtering. A silicon oxynitride film having a filmthickness of 150 nm is formed by plasma CVD in Embodiment 5. The firstinterlayer insulating film 249 is of course not limited to a siliconoxynitride film, and other insulating films containing silicon may alsobe used in a single layer or a lamination structure. Patterning isperformed next in order to form contact holes reaching the respectiveimpurity regions 232 a, 233 a, 235 a, 240 a, and 241 a.

Source wirings 251 to 255 and drain wirings 257 to 261 are formed next.(See FIG. 12C.) Note that it is preferable to use a material havingexcellent reflective properties such as a film having Al or Ag as itsmain constituent, or a lamination film of these films, as the wiringmaterial in Embodiment 5.

A second passivation film 268 is formed next having a thickness of 50 to500 nm (typically from 200 to 300 nm) as shown in FIG. 13A. A 300 nmthick silicon oxynitride film is used as the second passivation film 268in Embodiment 5. A silicon nitride film may also be substituted. Notethat it is effective to perform plasma processing using a gas containinghydrogen, such as H₂ or NH₃, in advance of the formation of the siliconoxynitride film.

A second interlayer insulating film 269 made from an organic resin isformed next. A material such as polyimide, polyamide, acrylic, or BCB(benzocyclobutene) can be used as the organic resin. In particular, itis preferable to use acrylic having superior levelness, because thesecond interlayer insulating film 269 has a strong implication as aleveling film. In Embodiment 5, an acrylic film is formed having a filmthickness capable of sufficiently leveling the steps formed by the TFTs.It is preferable that the film thickness be 1 to 5 μm (more preferablybetween 2 and 4 μm).

A contact hole for reaching the drain wiring 259 is then formed in thesecond interlayer insulating film 269 and in the second passivation film268, and a cathode electrode 270 of the photodiode is formed so as tocontact the drain wiring 259. An aluminum film formed by sputtering isused as the cathode electrode 270 in Embodiment 5, but other metals, forexample, titanium, tantalum, tungsten, and copper can also be used.Furthermore, a lamination film of titanium, aluminum, and titanium mayalso be used.

Patterning is performed after forming an amorphous silicon filmcontaining hydrogen on the entire surface of the substrate, forming aphotoelectric conversion layer 271. A transparent conductive film isthen formed on the entire surface of the substrate. A 200 nm thick ITOfilm is formed as the transparent conductive film by sputtering inEmbodiment 5. The transparent conductive film is then patterned, formingan anode electrode 272. (See FIG. 13B.)

A third interlayer insulating film 273 is formed next as shown in FIG.14A. A level surface can be obtained by using a resin such as polyimide,polyamide, polyimide amide, or acrylic as the third interlayerinsulating film 273. A polyimide film having a thickness of 0.7 μm isformed over the entire substrate surface as the third interlayerinsulating film 273 in Embodiment 5.

Next, a contact hole for reaching the drain wiring 261 is formed in thethird interlayer insulating film 273, in the second interlayerinsulating film 269, and in the second passivation film 268, and a pixelelectrode 275 is formed. Further, a contact hole for reaching the anodeelectrode 272 is formed in the third interlayer insulating film 273, anda sensor wiring 274 is formed. An aluminum alloy film (an aluminum filmcontaining 1 wt % of titanium) is formed with a thickness of 300 nm inEmbodiment 5. Patterning is then performed, forming the sensor wiring274 and the pixel electrode 275 at the same time.

Next, as shown in FIG. 14B, a bank 276 made from a resin material isformed. The bank 276 may be formed by patterning an acrylic film or apolyimide film having a thickness of 1 to 2 μm. The bank 276 may beformed along and on the source wiring 254, and it may also be formedalong and on a gate wiring (not shown in the figures). Note that thebank 276 may also be used as a shielding film by mixing a material suchas a pigment into the resin material forming the bank 276.

A light emitting layer 277 is formed next. Specifically, an organic ELmaterial which becomes the light emitting layer 277 is dissolved in asolvent such as chloroform, dichloromethane, xylene, toluene, ortetrahydrofuran and then applied. The solvent is then driven off byperforming heat treatment. A film (light emitting layer) is thus formedfrom the organic EL material.

Note that although only one pixel is shown in the figures in Embodiment5, a light emitting layer that emits red color light, a light emittinglayer that emits green color light, and a light emitting layer thatemits blue color light are all formed at the same time at this point inthe case where an information device which performs color display ismanufactured, cyano-polyphenylene-vinylene is used for the lightemitting layer that emits red color light, polyphenylene-vinylene isused for the light emitting layer that emits green color light, andpolyalkyl-phenylene is used for the light emitting layer that emits bluecolor light in Embodiment 5. The respective layers are formed with athickness of 50 nm. Further, 1,2-dichloromethane is used as the solvent,and heat treatment is performed for 1 to 5 minutes at a temperature of80 to 150° C. using a hot plate, thereby volatilizing the solvent.

A one layer structure comprised of a light emitting layer is taken forthe EL layer in Embodiment 5, but other layers such as a hole injectinglayer, a hole transporting layer, an electron injecting layer, and anelectron transporting layer may also be formed. Many examples ofcombination have already been reported, and any of the structures may beused.

An anode 279 made from a transparent conductive film is formed with athickness of 120 nm as an opposing electrode after forming the lightemitting layer 277. The transparent conductive film in which 10 to 20 wt% of zinc oxide is added to indium oxide is used in Embodiment 5. It ispreferable to form the anode 279 using evaporation at room temperatureas the film formation method so as not to damage the light emittinglayer 277.

A fourth interlayer insulating film 280 is then formed as shown in FIG.14B after forming the anode 279. A level surface can be obtained byusing a resin such as polyimide, polyamide, polyimide amide, or acrylicas the fourth interlayer insulating film 280. A 0.7 μm thick polyimidefilm is formed over the entire substrate surface as the fourthinterlayer insulating film 280 in Embodiment 5.

A substrate having a structure like that shown in FIG. 14B (hereafterreferred to as a TFT substrate) is thus completed. Note that it iseffective to perform processing in succession up to the formation of thefourth interlayer insulating film 280, without exposure to theatmosphere, by using a multi-chamber method (or an in-line method) thinfilm formation apparatus after forming the bank 276.

The buffer TFT 304, the selection TFT 305, the reset TFT 303, thephotodiode 306, the switching TFT 301, the EL driver TFT 302, and the ELelement 281 can thus be formed on the same substrate.

Note that the TFTs structuring respective driver circuits (an EL displaysource signal line driver circuit, an EL display gate signal line drivercircuit, a sensor source signal line driver circuit, and a sensor gatesignal line driver circuit) can also be manufactured similarly inaccordance with the above manufacturing process. The driver circuits canthus be formed on the same substrate as the combination display portionand input portion.

Note that it is possible to implement the present embodiment by freelybeing combined with any of Embodiments 1 to 4.

Embodiment 6

In this embodiment, an example of manufacturing the information deviceusing the present invention is described with reference to FIGS. 6A to6C.

FIG. 6A is a top view of an EL display device, FIG. 6B is a sectionalview taken along a line A-A′ of FIG. 6A, and FIG. 6C is a sectional viewtaken along a line B-B′ of FIG. 6A.

A seal member 4009 is provided so as to surround a combination ofdisplay portion and input portion 4002, a source signal line drivercircuit 4003 a and 4003 b for a sensor and an EL element, and the gatesignal line driver circuits 4004 a and 4004 b for a sensor and an ELelement, which are provided on a substrate 4001. Further, a sealingmember 4008 is provided over the combination of display portion andinput portion 4002, the source signal line driver circuit 4003 a and4003 b for a sensor and an EL element, and the gate signal line drivercircuits 4004 a and 4004 b for a sensor and an EL element. Thus, thecombination of display portion and input portion 4002, the source signalline driver circuit 4003 a and 4003 b for a sensor and an EL element,and the first and the second gate signal line driver circuits 4004 a and4004 b for a sensor and an EL element are sealed with a filler 4210 andby the substrate 4001, the seal member 4009, and the sealing member4008.

Further, the combination of display portion and input portion 4002, thesource signal line driver circuit 4003 a and 4003 b for a sensor and anEL element, and the gate signal line driver circuits 4004 a and 4004 bfor a sensor and an EL element provided on the substrate 4001 include aplurality of TFTs. FIG. 6B typically shows a reset TFTs (TFTs forapplying a reverse bias heating to a photodiode) 4201 included in thecombination of display portion and input portion 4002, an EL driver TFT(a TFT for controlling current to an EL element) 4202 and the photodiode4211, which are formed on a base film 4010.

In this embodiment, the n-channel TFT fabricated by a well-known methodare used as the reset TFTs 4201, and a p-channel TFT fabricated by awell-known method is used as the EL driver TFT 4202. Further, thestorage capacitor (not shown in the figure) connected to the gate of theEL driver TFT 4202 is provided at the combination of display portion andinput portion 4002.

A first interlayer insulating film (flattening film) 4311 is formed onthe reset TFTs 4201 and the EL driver TFT 4202. Next, the secondinterlayer insulating film (flattening film) 4302, and a photodiode 421Iis formed on thereon. Then, the third interlayer insulating film 4403 isformed, and a pixel electrode (anode) 4203 electrically connected to adrain of the EL driver TFT 4202 is formed thereon. A transparentconductive film having a high work function is used as the pixelelectrode 4203. A compound of indium oxide and tin oxide, a compound ofindium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide canbe used for the transparent conductive film. Further, the transparentconductive film added with gallium may be used.

An insulating film 4404 is formed on the pixel electrode 4203, and anopening portion is formed in the insulating film 4404 over the pixelelectrode 4203. In this opening portion, an EL (electro-luminescence)layer 4204 is formed on the pixel electrode 4203. A well-known organicEL material or inorganic EL material can be used for the EL layer 4204.Although the organic EL material includes a low molecular system(monomer system) and a high molecular system (polymer system), eithermay be used.

As a formation method of the EL layer 4204, a well-known evaporationtechnique or coating technique may be used. The structure of the ELlayer may be a laminate structure obtained by freely combining a holeinjection layer, a hole transporting layer, a light emitting layer, anelectron transporting layer, or an electron injection layer, or a singlelayer structure.

A cathode 4205 made of a conductive film (typically a conductive filmcontaining aluminum, copper or silver as its main ingredient, or alaminate film of those and another conductive films) having a lightshielding property is formed on the EL layer 4204. It is desirable thatmoisture and oxygen existing on the interface between the cathode 4205and the EL layer 4204 are removed to the utmost. Accordingly, it isnecessary to make such contrivance that the EL layer 4204 is formed in anitrogen or rare gas atmosphere, and the cathode 4205 is formed whilethe EL layer is not exposed to oxygen or moisture. In this embodiment, amulti-chamber system (cluster tool system) film forming apparatus isused, so that the film formation as described above is enabled. Apredetermined voltage is applied to the cathode 4205.

In the manner as described above, an EL element 4303 constituted by thepixel electrode (anode) 4203, the EL layer 4204, and the cathode 4205are formed. Then, a protection film 4209 is formed on the insulatingfilm 4404 so as to cover the EL element 4303. The protection film 4209is effective to prevent oxygen, moisture and the like from penetratinginto the EL element 4303.

Reference numeral 4005 designates a drawing wiring line connected to apower supply line and is electrically connected to a source region ofthe EL driver TFT 4202. The drawing wiring line 4005 passes between theseal member 4009 and the substrate 4001, and is electrically connectedto an FPC wiring line 4301 included in an FPC 4006 through ananisotropic conductive film 4300.

As the sealing member 4008, a glass member, a metal member (typically, astainless member), a ceramic member, or a plastic member (including aplastic film) can be used. As the plastic member, all FRP(Fiberglass-Reinforced Plastics) plate, a PVF (polyvinyl fluoride) film,a Mylar film, a polyester film or an acryl resin film can be used.Further, a sheet having such a structure that an aluminum foil isinterposed between PVF films or Mylar films can also be used.

However, in the case when the radiation direction of light from the ELelement is directed toward the side of a cover member, the cover membermust be transparent. In this case, a transparent material such as aglass plate, a plastic plate, a polyester film, or an acryl film isused.

As the filler 4210, in addition to an inert gas such as nitrogen orargon, ultraviolet ray curing resin or thermosetting resin can be used,and PVC (polyvinyl chloride), acryl, polyimide, epoxy resin, siliconeresin, PVB (polyvinyl butyral), or EVA (ethylene-vinyl acetate) can beused. In this embodiment, nitrogen was used as the filler.

Further, in order to expose the filler 4210 to a hygroscopic material(preferably, barium oxide) or a material capable of adsorbing oxygen, arecess portion 4007 is provided on the surface of the sealing member4008 on the side of the substrate 4001 and the hygroscopic material orthe material 4207 capable of adsorbing oxygen is disposed. Then, inorder to prevent the hygroscopic material or the material 4207 capableof adsorbing oxygen from scattering, the hygroscopic material or thematerial capable of adsorbing oxygen are held in the recess portion 4007by a recess cover member 4208. Note that, the recess cover member 4208is formed into a fine mesh, and has such a structure that air ormoisture is permeated and the hygroscopic material or the material 4207capable of adsorbing oxygen is not permeated. The deterioration of theEL element 4303 can be suppressed by providing therewith the hygroscopicmaterial or the material 4207 capable of adsorbing oxygen.

As shown in FIG. 6C, at the same time as the formation of the pixelelectrode 4203, a conductive film 4203 a is formed to be in contact withthe drawing wiring line 4005.

The anisotropic conductive film 4300 includes a conductive filler 4300a. The substrate 4001 and the FPC 4006 are thermally compressed, so thatthe conductive film 4203 a on the substrate 4001 and the FPC wiring line4301 on the FPC 4006 are electrically connected through the conductivefiller 4300 a.

Further, this embodiment can be implemented by freely combined withEmbodiments 1 to 5.

Embodiment 7

An example of manufacturing a photoelectric conversion element of aninformation device of the present invention using an organic compound isexplained in Embodiment 7.

An example of using a photodiode as the photoelectric conversion elementis explained.

An organic compound is used as the photoelectric conversion layerconsisting of the photodiode. Specifically, compounds such as an azodye, a polycyclic compound such as perillen, a phthalocyanine pigment,and an ionic pigment can be used. Note that the photoelectric conversionlayer is referred to as an electric charge generating layer here.

Further, layers such as an electric charge injection barrier layer andan electric charge transporting layer may also be formed in addition tothe electric charge generating layer.

Low molecular weight materials such as a hydrazone derivative, astilbenzene derivative, and a triphenylamine derivative, and highmolecular weight materials such as a polysilane derivative can beutilized for the electric charge transporting layer.

The responsiveness to light of the photodiode can be improved by formingthis type of electric charge transporting layer.

Further, a material such as a copolymer nylon can be used as theelectric charge injection barrier layer.

A method of manufacturing this type of photodiode having a laminationstructure of an electric charge injection barrier layer, an electriccharge generating layer, and an electric charge transporting layer isexplained using FIG. 19.

An anode electrode 991 is formed from an ITO film, and an electriccharge injection barrier layer 992, an electric charge generating layer993, an electric charge transporting layer 994, and a cathode electrode996 are formed in order on the anode electrode 991.

A copolymer nylon layer is applied as the electric charge injectionbarrier layer 992 here.

The electric charge generating layer 993 is then formed by applying amaterial in which an azo dye is distributed in a binder resin.

The electric charge transporting layer 994 is formed next by applying amaterial in which a hydrazone derivative is distributed in a binderresin.

Lastly, the cathode electrode 996 is formed by aluminum, and thephotodiode 997 is completed.

Note that the photodiode structure is not limited to this structure. Itis not always necessary to form the electric charge injection barrierlayer or the electric charge transporting layer.

Further, the anode electrode, the cathode electrode, the electric chargeinjection barrier layer, the electric charge generating layer, and theelectric charge transporting layer are not limited to the above statedmaterials, and known materials can be freely used.

Compared to photodiodes using inorganic compounds such assemiconductors, those using organic compounds have the followingadvantages: it is possible to manufacture large surface areaphotodiodes; organic compound photodiodes have abundant elasticity; andorganic compound photodiodes have superior processing properties.

Note that it is possible to implement the present embodiment by freelycombining it with any of Embodiments 1 to 6.

Embodiment 8

Electronic devices applying an information device of the presentinvention are explained in Embodiment 8. Devices such as portableinformation terminals (PDAs, portable telephones, electronic books, andthe like) can be given as examples of applying an information device ofthe present invention.

FIG. 15A is a schematic diagram of a PDA. The PDA has a combinationdisplay portion and input portion 1901, an input pen 1902, an operationkey 1903, an external connection port 1904, and an electric power sourceswitch 1905. An information device of the present invention can be usedin the combination display portion and input portion 1902 of the PDA.

FIG. 15B is a schematic diagram of an electronic book. The electronicbook has a combination display portion and input portion 1911, an inputpen 1912, operation keys 1913, and a recording medium 1914. Aninformation device of the present invention can be used in thecombination display portion and input portion 1911.

FIG. 21A and FIG. 21B are examples of applying an information device ofthe present invention to a portable information terminal having afunction of personal recognition.

The term personal recognition refers here to a function of comparinginformation recorded in advance with information input later, and thenusing the two sets of information to judge whether or not the sameperson is indicated.

FIG. 21A shows a portable information terminal 2183. The portableinformation terminal 2183 has components such as an input pen 2181, acombination display portion and input portion 2184, operation keys 2185,an external connection port 2186, and an electric power source switch2187.

A palm print can be read in by placing a hand 2188 on the combinationdisplay portion and input portion 2184 in accordance with a method ofusing the combination display portion and input portion 2184 as an imagesensor, like the method shown in Embodiment 4.

The palm print read in can be used as information for identifyingindividual person (individual information), and recognition processingcan be performed.

Note that the individual information used in the recognition process isnot limited to only palm prints. Other biological information such asfinger prints can also be freely used.

Further, these types of individual information for performingrecognition can be freely combined and then used.

FIG. 21B is a portable information device having the same structure asthat shown by FIG. 21A, and a case of performing recognition processingby a different method is explained.

Handwriting 2191 information input to the combination display portionand input portion 2184 by the input pen 2181 is used here forrecognition processing.

Note that individual information such as handwriting input by the inputpen, and individual information such as palm prints and fingerprintsinput by using the image sensor can be freely combined and applied to aportable information terminal that performs recognition of its owner.

The applicable range of the present invention is extremely wide, and itis possible to apply the present invention to electronic devices of allfields. Further, the electronic devices of Embodiment 8 can be realizedusing structure in which Embodiments 1 to 7 are freely combined.

There are problems in areas such as image visibility, endurance of thedevice, precision, miniaturization, and electric power consumption in aninformation device having a conventional resistive film method oroptical method pen input function.

Both EL elements and photoelectric conversion elements are arranged ineach pixel of a display device in an information device of the presentinvention having a pen input function. Information input is performed bythe input of light to the photoelectric conversion elements inaccordance with a pen that reflects light by a pen tip. An informationdevice with a pen input function, capable of displaying a clear imagewithout loss of brightness in the displayed image, having superiorendurance, capable of being miniaturized, and having good precision callthus be obtained.

1. A portable electronic book comprising: a plurality of pixels arrangedin a matrix shape, each of the plurality of pixels comprising an ELelement and a photoelectric conversion element over a same substrate,wherein the EL element is located above the photoelectric conversionelement with an interlayer insulating film interposed therebetween; ameans for making the EL element emit light; an input pen for reflectinga light emitted by the EL element and for inputting the light to thephotoelectric conversion element of a portion of pixels among theplurality of pixels; and a means for detecting coordinates of theportion of the pixels.
 2. A portable electronic book according to claim1, wherein each of the plurality of pixels comprises a selection TFT, abuffer TFT, and a reset TFT; the means of detecting the intensity oflight emitted to the photoelectric conversion elements comprising: aplurality of sensor output wirings; a plurality of sensor gate signallines; a plurality of reset gate signal lines; a plurality of sensorelectric power source lines; a sensor source signal line driver circuitinto which signals from the plurality of sensor output wirings areinput; and a sensor gate signal line driver circuit from which signalsare output to the plurality of sensor gate signal lines and theplurality of reset gate signal lines, wherein: a gate electrode of theselection TFT is connected to one of the plurality of sensor gate signallines; one of a source region and a drain region of the selection TFT isconnected to one of the plurality of sensor output wirings, and theremaining one of the source region and the drain region of the selectionTFT is connected to a source region of the buffer TFT; a drain region ofthe buffer TFT is connected to one of the plurality of sensor electricpower source lines; a gate electrode of the buffer TFT is connected to aphotodiode and a source region or a drain region of the reset TFT; oneof the source region and the drain region of the reset TFT, which is notconnected to the buffer TFT, is connected to one of the plurality ofsensor electric power source lines; and a gate electrode of the resetTFT is connected to one of the plurality of reset gate signal lines. 3.A portable electronic book according to claim 2, wherein the sensorsource signal line driver circuit and the sensor gate signal line drivercircuit are formed over the same substrate as the EL element and thephotoelectric conversion element.
 4. A portable electronic bookaccording to claim 1, wherein each of the plurality of pixels comprisesa switching TFT and an EL driver TFT; the means of making the ELelements emit light comprising: a plurality of EL display source signallines; a plurality of EL display gate signal lines; a plurality ofelectric power source supply lines; an EL display source signal linedriver circuit for outputting signals to the plurality of EL displaysource signal lines; and an EL display gate signal line driver circuitfor outputting signals to the plurality of EL display gate signal lines,wherein: a gate electrode of the switching TFT is connected to one ofthe plurality of EL display gate signal lines; one of a source regionand a drain region of the switching TFT is connected to one of theplurality of EL display source signal lines, and the other of the sourceregion and the drain region of the switching TFT is connected to a gateelectrode of the EL driver TFT; and one of a source region and a drainregion of the EL driver TFT is connected to one of the plurality ofelectric power source supply lines, and the other of the source regionand the drain region of the EL driver TFT is connected to the ELelement.
 5. A portable electronic book according to claim 4, wherein theEL display source signal line driver circuit and the EL display gatesignal line driver circuit are formed over the same substrate as the ELelement and the photoelectric conversion element.
 6. A portableelectronic book according to claim 1, wherein the photoelectricconversion element comprises a photodiode.
 7. A portable electronic bookaccording to claim 6, wherein the photodiode comprises an anodeelectrode, a cathode electrode, and a photoelectric conversion layercomprising an organic material sandwiched between the anode electrodeand the cathode electrode.
 8. A portable electronic book according toclaim 6, wherein the photodiode comprises a p-type semiconductor layer,an n-type semiconductor layer, and a photoelectric conversion layercomprising an amorphous semiconductor sandwiched between the p-typesemiconductor layer and the n-type semiconductor layer.
 9. A portableelectronic book according to claim 1, wherein the information device hasa means for irradiating a light emitted from the EL element to a surfaceof an object, and inputting the light reflected by the surface of theobject to the photoelectric conversion element.
 10. A portableelectronic book according to claim 9, wherein an information of thesurface of the object is biological information comprising at least oneselected from the group consisting of a palm print and a finger print.11. A portable electronic book comprising: a plurality of pixelsarranged in a matrix shape, each of the plurality of pixels comprisingan EL element and a photoelectric conversion element over a samesubstrate, wherein the EL element is located above the photoelectricconversion element with an interlayer insulating film interposedtherebetween; a means for making the EL element emit light; an input penfor reflecting a light emitted by the EL element and for inputting thelight to the photoelectric conversion element of a portion of pixelsamong the plurality of pixels; and a means for detecting an intensity ofthe light irradiated to the photoelectric conversion element.
 12. Aportable electronic book according to claim 11, wherein each of theplurality of pixels comprises a selection TFT, a buffer TFT, and a resetTFT; the means of detecting the intensity of light emitted to thephotoelectric conversion elements comprising: a plurality of sensoroutput wirings; a plurality of sensor gate signal lines; a plurality ofreset gate signal lines; a plurality of sensor electric power sourcelines; a sensor source signal line driver circuit into which signalsfrom the plurality of sensor output wirings are input; and a sensor gatesignal line driver circuit from which signals are output to theplurality of sensor gate signal lines and the plurality of reset gatesignal lines, wherein: a gate electrode of the selection TFT isconnected to one of the plurality of sensor gate signal lines; one of asource region and a drain region of the selection TFT is connected toone of the plurality of sensor output wirings, and the remaining one ofthe source region and the drain region of the selection TFT is connectedto a source region of the buffer TFT; a drain region of the buffer TFTis connected to one of the plurality of sensor electric power sourcelines; a gate electrode of the buffer TFT is connected to a photodiodeand a source region or a drain region of the reset TFT; one of thesource region and the drain region of the reset TFT, which is notconnected to the buffer TFT, is connected to one of the plurality ofsensor electric power source lines; and a gate electrode of the resetTFT is connected to one of the plurality of reset gate signal lines. 13.A portable electronic book according to claim 12, wherein the sensorsource signal line driver circuit and the sensor gate signal line drivercircuit are formed over the same substrate as the EL element and thephotoelectric conversion element.
 14. A portable electronic bookaccording to claim 11, wherein each of the plurality of pixels comprisesa switching TFT and an EL driver TFT; the means of making the ELelements emit light comprising: a plurality of EL display source signallines; a plurality of EL display gate signal lines; a plurality ofelectric power source supply lines; an EL display source signal linedriver circuit for outputting signals to the plurality of EL displaysource signal lines; and an EL display gate signal line driver circuitfor outputting signals to the plurality of EL display gate signal lines,wherein: a gate electrode of the switching TFT is connected to one ofthe plurality of EL display gate signal lines; one of a source regionand a drain region of the switching TFT is connected to one of theplurality of EL display source signal lines, and the other of the sourceregion and the drain region of the switching TFT is connected to a gateelectrode of the EL driver TFT; and one of a source region and a drainregion of the EL driver TFT is connected to one of the plurality ofelectric power source supply lines, and the other of the source regionand the drain region of the EL driver TFT is connected to the ELelement.
 15. A portable electronic book according to claim 14, whereinthe EL display source signal line driver circuit and the EL display gatesignal line driver circuit are formed over the same substrate as the ELelement and the photoelectric conversion element.
 16. A portableelectronic book according to claim 11, wherein the photoelectricconversion element comprises a photodiode.
 17. A portable electronicbook according to claim 16, wherein the photodiode comprises an anodeelectrode, a cathode electrode, and a photoelectric conversion layercomprising an organic material sandwiched between the anode electrodeand the cathode electrode.
 18. A portable electronic book according toclaim 16, wherein the photodiode comprises a p-type semiconductor layer,an n-type semiconductor layer, and a photoelectric conversion layercomprising an amorphous semiconductor sandwiched between the p-typesemiconductor layer and the n-type semiconductor layer.
 19. A portableelectronic book according to claim 11, wherein the information devicehas a means for irradiating a light emitted from the EL element to asurface of an object, and inputting the light reflected by the surfaceof the object to the photoelectric conversion element.
 20. A portableelectronic book according to claim 19, wherein an information of thesurface of the object is biological information comprising at least oneselected from the group consisting of a palm print and a finger print.21. A portable electronic book comprising: a plurality of pixelsarranged in a matrix shape, each of the plurality of pixels comprisingan EL element and a photoelectric conversion element over a samesubstrate, wherein the EL element is located above the photoelectricconversion element with an interlayer insulating film interposedtherebetween; a means for making the EL element emit light; and a meansfor detecting coordinates of the portion of the pixels.
 22. A portableelectronic book according to claim 21, wherein each of the plurality ofpixels comprises a selection TFT, a buffer TFT, and a reset TFT; themeans of detecting the intensity of light emitted to the photoelectricconversion elements comprising: a plurality of sensor output wirings; aplurality of sensor gate signal lines; a plurality of reset gate signallines; a plurality of sensor electric power source lines; a sensorsource signal line driver circuit into which signals from the pluralityof sensor output wirings are input; and a sensor gate signal line drivercircuit from which signals are output to the plurality of sensor gatesignal lines and the plurality of reset gate signal lines, wherein: agate electrode of the selection TFT is connected to one of the pluralityof sensor gate signal lines; one of a source region and a drain regionof the selection TFT is connected to one of the plurality of sensoroutput wirings, and the remaining one of the source region and the drainregion of the selection TFT is connected to a source region of thebuffer TFT; a drain region of the buffer TFT is connected to one of theplurality of sensor electric power source lines; a gate electrode of thebuffer TFT is connected to a photodiode and a source region or a drainregion of the reset TFT; one of the source region and the drain regionof the reset TFT, which is not connected to the buffer TFT, is connectedto one of the plurality of sensor electric power source lines; and agate electrode of the reset TFT is connected to one of the plurality ofreset gate signal lines.
 23. A portable electronic book according toclaim 22, wherein the sensor source signal line driver circuit and thesensor gate signal line driver circuit are formed over the samesubstrate as the EL element and the photoelectric conversion element.24. A portable electronic book according to claim 21, wherein each ofthe plurality of pixels comprises a switching TFT and an EL driver TFT;the means of making the EL elements emit light comprising: a pluralityof EL display source signal lines; a plurality of EL display gate signallines; a plurality of electric power source supply lines; an EL displaysource signal line driver circuit for outputting signals to theplurality of EL display source signal lines; and an EL display gatesignal line driver circuit for outputting signals to the plurality of ELdisplay gate signal lines, wherein: a gate electrode of the switchingTFT is connected to one of the plurality of EL display gate signallines; one of a source region and a drain region of the switching TFT isconnected to one of the plurality of EL display source signal lines, andthe other of the source region and the drain region of the switching TFTis connected to a gate electrode of the EL driver TFT; and one of asource region and a drain region of the EL driver TFT is connected toone of the plurality of electric power source supply lines, and theother of the source region and the drain region of the EL driver TFT isconnected to the EL element.
 25. A portable electronic book according toclaim 24, wherein the EL display source signal line driver circuit andthe EL display gate signal line driver circuit are formed over the samesubstrate as the EL element and the photoelectric conversion element.26. A portable electronic book according to claim 21, wherein thephotoelectric conversion element comprises a photodiode.
 27. A portableelectronic book according to claim 26, wherein the photodiode comprisesan anode electrode, a cathode electrode, and a photoelectric conversionlayer comprising an organic material sandwiched between the anodeelectrode and the cathode electrode.
 28. A portable electronic bookaccording to claim 26, wherein the photodiode comprises a p-typesemiconductor layer, an n-type semiconductor layer, and a photoelectricconversion layer comprising an amorphous semiconductor sandwichedbetween the p-type semiconductor layer and the n-type semiconductorlayer.
 29. A portable electronic book according to claim 21, wherein theinformation device has a means for irradiating a light emitted from theEL element to a surface of an object, and inputting the light reflectedby the surface of the object to the photoelectric conversion element.30. A portable electronic book according to claim 29, wherein aninformation of the surface of the object is biological informationcomprising at least one selected from the group consisting of a palmprint and a finger print.
 31. A portable electronic book comprising: aplurality of pixels arranged in a matrix shape, each of the plurality ofpixels comprising an EL element and a photoelectric conversion elementover a same substrate, wherein the EL element is located above thephotoelectric conversion element with an interlayer insulating filminterposed therebetween; a means for making the EL element emit light;and a means for detecting an intensity of the light irradiated to thephotoelectric conversion element.
 32. A portable electronic bookaccording to claim 31, wherein each of the plurality of pixels comprisesa selection TFT, a buffer TFT, and a reset TFT; the means of detectingthe intensity of light emitted to the photoelectric conversion elementscomprising: a plurality of sensor output wirings; a plurality of sensorgate signal lines; a plurality of reset gate signal lines; a pluralityof sensor electric power source lines; a sensor source signal linedriver circuit into which signals from the plurality of sensor outputwirings are input; and a sensor gate signal line driver circuit fromwhich signals are output to the plurality of sensor gate signal linesand the plurality of reset gate signal lines, wherein: a gate electrodeof the selection TFT is connected to one of the plurality of sensor gatesignal lines; one of a source region and a drain region of the selectionTFT is connected to one of the plurality of sensor output wirings, andthe remaining one of the source region and the drain region of theselection TFT is connected to a source region of the buffer TFT; a drainregion of the buffer TFT is connected to one of the plurality of sensorelectric power source lines; a gate electrode of the buffer TFT isconnected to a photodiode and a source region or a drain region of thereset TFT; one of the source region and the drain region of the resetTFT, which is not connected to the buffer TFT, is connected to one ofthe plurality of sensor electric power source lines; and a gateelectrode of the reset TFT is connected to one of the plurality of resetgate signal lines.
 33. A portable electronic book according to claim 32,wherein the sensor source signal line driver circuit and the sensor gatesignal line driver circuit are formed over the same substrate as the ELelement and the photoelectric conversion element.
 34. A portableelectronic book according to claim 31, wherein each of the plurality ofpixels comprises a switching TFT and an EL driver TFT; the means ofmaking the EL elements emit light comprising: a plurality of EL displaysource signal lines; a plurality of EL display gate signal lines; aplurality of electric power source supply lines; an EL display sourcesignal line driver circuit for outputting signals to the plurality of ELdisplay source signal lines; and an EL display gate signal line drivercircuit for outputting signals to the plurality of EL display gatesignal lines, wherein: a gate electrode of the switching TFT isconnected to one of the plurality of EL display gate signal lines; oneof a source region and a drain region of the switching TFT is connectedto one of the plurality of EL display source signal lines, and the otherof the source region and the drain region of the switching TFT isconnected to a gate electrode of the EL driver TFT; and one of a sourceregion and a drain region of the EL driver TFT is connected to one ofthe plurality of electric power source supply lines, and the other ofthe source region and the drain region of the EL driver TFT is connectedto the EL element.
 35. A portable electronic book according to claim 34,wherein the EL display source signal line driver circuit and the ELdisplay gate signal line driver circuit are formed over the samesubstrate as the EL element and the photoelectric conversion element.36. A portable electronic book according to claim 31, wherein thephotoelectric conversion element comprises a photodiode.
 37. A portableelectronic book according to claim 36, wherein the photodiode comprisesan anode electrode, a cathode electrode, and a photoelectric conversionlayer comprising an organic material sandwiched between the anodeelectrode and the cathode electrode.
 38. A portable electronic bookaccording to claim 36, wherein the photodiode comprises a p-typesemiconductor layer, an n-type semiconductor layer, and a photoelectricconversion layer comprising an amorphous semiconductor sandwichedbetween the p-type semiconductor layer and the n-type semiconductorlayer.
 39. A portable electronic book according to claim 31, wherein theinformation device has a means for irradiating a light emitted from theEL element to a surface of an object, and inputting the light reflectedby the surface of the object to the photoelectric conversion element.40. A portable electronic book according to claim 39, wherein aninformation of the surface of the object is biological informationcomprising at least one selected from the group consisting of a palmprint and a finger print.